Energy Used in Daily Life
Multiple Choice Question
Circle the correct answer to the following questions.
1. What is called for the process of transmission of heat in solid without actual movement of the molecules?a) conductor b) convection c) radiation d) Conduction
2. Which of the following is the application of radiation of heat in our daily life?a) Boiling water and other liquids.
b) The circulation of blood in warm blooded animals.
c) Wearing white or light colored clothes in summer season as it absorbs less heat.
d) Electric fan and air conditioner and fans used in summer.
3. Which of the following is not the greenhouse gas?a) carbon monoxide b) carbon dioxide
c) Chlorofluro carbon d) methane
4. Where is the position of object in a concave mirror to form erect and virtual image?a) Object is kept at C. b) Object is kept at F.
c) object is kept between F and O. d) Object is kept between C and F.
5. Which is the unit to measure the loudness of sound?a) decibel b) hertz c) Watt d) meter
6. What is the transmission of heat due to the actual movement of molecules?a) conduction b) convection c) radiation d) temperature
7. What mirror is used to look at our face in our daily life?a) plane mirror b) concave mirror
c) convex mirror d) spherical mirror
8. Which mirrors can make a real image of an object?a) a) plane mirror b) concave mirror
c) convex mirror d) spherical mirror
9. What kind of mirrors is called a concave mirrors?a) Plane mirror b) converging mirror
b) diverging mirror d) simple mirror
10. Which is the time the number of sound wave produced is called frequency?a) 1 second b) 2 second c) 3 second d) 4 second
11. What is the range of intensity of sound in normal conversation?a) 0-20 dB b) 20-40 dB c) 40-60 dB d) 60-70 dB
12. What is the threshold of hearing for deafness?a) 90 dB b) 80 dB c) 60 dB d) 55 dB
13. Vehicle has velocity of 20 meter per second towards East direction another vehicle has velocity of 15 meter per second in West direction. If they start to move from a point simultaneously what is the distance between them after 2 minutes?a) 4200 m b) 2400 m c) 1800 m d) 4500 m
14. If two cars A and B are moving with a velocity of 60 kilometer per hour and 80 kilometer per hour respectively in the same direction, what will be their relative velocity of B with respect to A?40km/hr b)20km/hr c) 140 km/hr d) 50 km/hr
15. Which is the unit of density?a) Kg/m3 b) Kg/liter c) Kg/cm3 d) kg/m
16. Which object floured on liquid?a) An object having less density than that of liquid.
b) An object having less mass.
c) An object having greater density than that of liquid.
d) An object having more mass.
17. On which direction does a liquid exert pressure?a) only upwards b) only downwards
c) only on lateral sides d) in all directions
18. A point is at the depth of 100 meter and acceleration due to gravity is 9.8 m/s2 how much pressure will be at that depth?a) 980 pa b) 9800 pa c) 98000 pa d) 980000 pa
Answers: 1(a), 2(c), 3(a), 4(d), 5((a), 6(b), 7(a), 8(b), 9((b), 10(a), 11(c), 12(b), 13(a), 14(b), 15(a), 16(a), 17(d), 18(b)
Group B
Very Short Questions [1 mark each]
What is transmission of heat?
The process of transfer of heat from one place to another place is called transmission of heat.
Give an example of convection.
Boiling of water is an example of convection.
What is the mode of transmission of heat in vacuum?
The mode of transmission of heat in vacuum is radiation.
Why is the exterior surface of the cooking tools is frequently coated with black material?
Black colour absorbs more heat and it helps in cooking food faster, conserves fuel and retain heat for longer time. So, exterior surface of the cooking tools is frequently coated with black material.
What is greenhouse effect?
The phenomena of trapping of solar heat of longer wavelength inside the earth's atmosphere is called greenhouse effect.
Define principal focus?
A point on the principal axis at which parallel beam of light after reflection by a mirror meets or appears to be meeting is called principal focus.
Write the SI unit of frequency.
The SI unit of frequency is Hertz (Hz).
What is the frequency of audible sound?
The frequency of audible sound is between 20 Hz to 20 Khz.
Write the relationship between intensity of sound and amplitude?
The intensity of sound is directly proportional to the square of amplitude i.e. a a2.
what is meant by noise?
The disturbance produce in environment by undesirable, loud and harsh sound is called noise or Sound pollution.
How does heat transmit from the sun to the earth?
Heat transmits from the sun to the earth through radiation.
What is wavelength?
The distance between any to consecutive crest or trough is called wavelength.
What is the relationship between speed of sound, wavelength and frequency.
Speed or sound is directly proportional to the product of wavelength and frequency. i.e. V=f*
Group C [Short Answer Questions] 2 marks each
Write any two differences between conduction and convection.
Two differences between conduction and convection are:
Conduction |
Convection |
1. The process of transfer of heat without the movement of molecules of material. 2. For example, when we touch a hot pan, heat is transferred from the pan to our hand through conduction. |
1. The process of transfer of heat in which heat is transferred by the movement of molecules. 2. For example, when we boil water, the heat transferred from the bottom of the container to the surface. |
Write any two differences between real image and virtual i
632341Two differences between real image and virtual image.
Real image | Virtual image |
1. Real image is formed when the reflected rays of light intersect at a point. | 1. Virtual image is formed when reflected rays appear to meet. |
2. Real image is always inverted. | 2. Virtual image is always erect. |
What is wavelength? Calculate the velocity of sound having frequency 1000 Hertz and wavelength 3.3 m.
The distance traveled by the wave while forming one complete wave is called wavelength.
Here,
Frequency(f)
= 1000 Hz
Wavelength()
= 3.3 m
Velocity
(v) = ?
We
have formula
V
= f *
Therefore,
V = 1000* 3.5
=3500
m/s
3. What is the center of curvature? Write any two uses of concave mirrors.
The center of the hollow glass sphere which the spherical mirror is a part is called center of curvature. Two uses of concave mirror are:
b) It is used as reflector in search light, torch light, etc.
Two differences between concave and convex mirror are:
Concave mirror | Convex mirror |
1. In concave mirror, the outer surface is polished and inner surface is reflecting surface. | 1. In convex mirror, the inner surface is polished and outer surface is reflecting surface. |
2. It always forms real image except when the object is between F and C. | 2. It always form virtual image. |
5. What is the unit of velocity of sound? What do you mean by frequency of sound wave is 20 Hertz?
The unit of velocity of sound is meter. The frequency of sound wave is 20 Hertz. It means that the 20 complete waves are produced in one second.
6. If speed of sound in areas 332 m/s and frequency is 100 Hz, calculate the wavelength.
Speed of sound (v) = 332 m/s
frequency (f)= 20 Hz
wave length () = ?
We have formula,
V= f *
or, 332 = 100 *
or = 332/100 = 3.32 m
7. Write the laws required to draw ray diagram in concave mirrors.
The laws required to draw re-diagram in concave mirror are:
a) A ray of light which is parallel to the principal axis of a concave mirror passes through its focus after reflection.
b) A ray of light passing through a center of curvature of a concave mirror is reflected back along the same path.
c) A ray of light passing through the focus of a concave mirror becomes parallel to the principal axis after reflection
8. What is frequency? Write it's SI unit.
The number of complete cycles made by a wave in one second is called frequency. Its si unit is Hertz (Hz).
9. Astronauts use an electronic device to communicate in space, why?
Sound wave is a mechanical wave which need medium for propagation. There is no medium for the propagation of sound in the space. So astronauts use an electronic device to communicate in this space.
10. If the speed of sound is 340 meter per second and the frequency is 100 Hertz, calculate the wavelength of the sound.
frequency (f)= 100 Hz
wave length () = ?
We have formula,
V= f *
or, 340 = 100 *
or = 340/100 = 3.40 m
Two differences between longitudinal wave and transverse wave are:
Longitudinal Wave | Transverse Wave |
1. In longitudinal wave the molecules of the vibrating particles move parallel with the propagation of the wave. | In transverse wave the molecules of the vibrating particles move perpendicular to the propagation of the wave. |
2. It consists of compression and rarefaction. | 2. It consists of crest and trough. |
13. Name the spherical mirror shown in the given figure. It is also called converging mirror, why?
The spherical mirror in the given figure is concave mirror. It is called converging mirror because the reflected rays of light from a concave mirror meet at a point.
14. Write any two differences between conductors and insulator?Two differences between conductor and insulator are:
Conductor | Insulator |
1. The materials which allow heat to flow through them are called conductors. | 1. The material which do not allow the heat to flow through them are insulator. |
2. Metals like silver, copper, iron are the examples of conductors. | 2. Materials like wood, plastics, asbestos are the insulators. |
Two differences between mechanical wave and electromagnetic wave are:
Mechanical Wave | Electromagnetic wave |
1. Mechanical wave requires medium for propagation. | 1. Electromagnetic wave does not require any medium for propagation. |
2. They do not cast shadow. | 2. they can cast sadow. |
Two differences between sea breeze and land breathe are given below:
Sea breeze | Land breeze |
1. The movement of air from sea to land is called sea breeze. | 1. the movement of air from land to sea is called land breeze. |
2. It occurs during night. | 2. It occurs during daytime. |
17. The mud house are cooler in summer and warmer in winter, why?
18. A teacup is usually made of porcelain, why?
20. We prefer light colored clothing in summer, why?
c) Center of curvature d) Focal length
a) Principal axis: An imaginary line passing through the center of curvature and pole of a mirror is called principal axis.
b) Focus: A point on the principal axis where parallel beam of light with principal axis meet after reflection through a mirror or appears to be meeting is called focus.
c) Center of curvature: The center of a hollow glass is sphere of which the spherical mirror is apart is called center of curvature.
d) Focal length: The distance between the pole of the mirror and principal focus is called focal length.
Concave mirror is also called a converging mirror, why?
See Group C QN 13
Concave mirror is used in solar stoves. Why?
The rays of light coming from the sun contains heat. A concave mirror reflect the solar rays at a point (on focus). As a result more amount of heat is collected at focus which make it faster to cook food in a solar stove. So, concave mirror is used in solar stoves.
Write any two differences between wavelength and amplitude.
Two differences between wavelength and amplitude are:
Wavelength
Amplitude
1. The distance traveled by a wave while forming a complete wave or cycle is called wavelength.
1. The maximum displacement of the vibrating particles from the mean position of the propagation of wave is called amplitude.
2. It is crucial in determining the frequency.
2. It is crucial in determining the loudness of sound.
Write any two differences between infrasound and audible sound.
Two differences between infrasound and audible sound.
Infrasound
Ultrasound
1. Infrasound has frequency below 20 Hz.
1. Ultrasound has frequency more than 20 Khz.
2. Sesmic waves are infrasound.
2. Bats and dolphins produces ultrasound.
Write any two differences between audible and ultrasound.
Two differences between audible and ultrasound are:
Audible sound
Ultrasound
1. Audible sound has frequency between 20 Hz to 20 KHz.
1. Ultrasound has frequency more than 20 KHz.
2. Sound produced from musical instrument, birds, animals, etc.
2. Sound produced by bats and dolphins etc are ultrasound.
The speed of sound remains the same on changing the frequency or wavelength of sound, why?
The speed of sound remains constant on changing the frequency or wavelength of sound because speed of sound depends upon properties of the medium through which it propagates. If the properties of the medium remains same, the velocity of sound remain same on changing the frequency or wavelength of sound.
The sound is heard fainter when the listener is moving away from the source of sound. Why?
As the sound travel, the energy it has spread around and there is decrease in the energy as the sound travel to longer distance. So, the sound is heard fainter when the listener is moving away from the source of sound.
Write down any two application of ultrasound.
Two applications of ultrasound are:
a) Doctors can identify the disease of inner body and locate the position of tumor with th help of ultrasound.
b) Bats produce ultrasound and detect the reflected sound to identify the prey or obstacle on the way.
Draw a neat and clean diagram of the sound wave.
Why is convex mirror called a diverging mirror?
Convex mirror is called diverging mirror because the reflected light ray from a convex mirror diverges in different direction.
Calculate the wavelength of sound wave if the speed of sound in air is 332m/s and its frequency is 10 Hz.
Here,
Speed of sound (v) = 332 m/s
frequency (f)= 10 Hz
wave length () = ?
We have formula,
V= f *
or, 340 = 10 *
or = 340/10 = 34.0 m
If 2×10-5 W/m2 intensity of sound spreads out in an area of 6m2 in 1 second, then calculate the energy carried by the sound wave.
Here,
Intensity of sound I = 2×10-5 w/m2.
Area (A)= 6m2
Power (P) = ?
We have formula,
I = P/A
or, P = I * A
or P = 2×10-5 *6
=1.2×10-4 watt
Group D : Long answer questions. [4 marks each]
1. What is radiation? Write the structure and function of thermos.
An image formed by the actual intersection of the reflected rays of light from a mirror is called real image.
Draw a ray diagram for the image formed by a concave mirror if the object is placed between F and P. Write its two nature.
The nature of the image formed is
The image is virtual, magnified and erect.
Complete the given ray diagram and write any two nature of the image so formed.
The image is real, inverted, highly magnified and formed at infinity.
Two nature of the image are
- The image is virtual, diminished, erect.
Complete the given ray diagram and write any two nature of the image so formed.
Write any two uses of convex mirror. Complete the given ray diagram and write any one property of the image through formed.
Two uses of concave mirror are:
a) Convex mirror is used in street light as reflector.
b) It is used as a rear view mirror in automobiles.
The completed ray diagram of the given figure is:
Answer the following questions on the basis of the given ray diagram.
a) Complete the given ray diagram.
b) Write any two features of the image so formed in the ray diagram.
Nature of the image formed in the ray diagram are:
Real, inverted, magnified and formed beyond C.
write to causes and effect of sound pollution.
Two causes of sound pollution are:
a) Noise of television, radio, power music system, washing machine, mixture grinder, vacuum cleaner, etc. at homes.
b) Loudspeaker, explosion, vehicle horn, sound from construction work in our surroundings.
Two effect of sound pollution are:
a) Noise reduces the concentration, increases stress, causes headache, etc.
b) It causes anger, irritation and high blood pressure.
What is convection of heat? Write down any three application of convection in daily life.
The process of transmission of heat in which heat is carried by the molecules. Three application of convection are:
a) Ventilators in room are made near the ceiling to allow the hot air to raise and cold air could pass through doors and windows.
b) Land breeze and sea breeze occur due to the convection.
c) Air conditioners are placed at a great height so that cool air form the air conditioner sinks and hot air pass out.
What is radiation process? Write down three applications of radiation in daily life.
The process of transmission of heat without any medium is called radiation. Three application of radiation in our daily life are:
a) Electric room heater has curve polished surface behind the rods to reflect the radiation falling on it.
b) Solar heater and solar cooker work on the radiation of solar energy.
c) Radiators of cars and air conditioners absorbs heat radiation.
What is electromagnetic wave? Give any three examples of electromagnetic waves.
The wave which does not require any medium for propagation is electromagnetic wave. Three examples of electromagnetic waves are: ultraviolet rays, gamma rays and x rays.
Draw a labeled diagram of a thermos flask.
Draw the re-diagram of the image formed by concave mirror when the object is kept: a) Beyond C b) at infinity c) between C and F d) at C
- What is ultrasonic wave? Write down the names of any two animals that can produce and hear ultrasound. Write any two applications of ultrasonic wave.
a) Doctors can identify the disease of inner body and locate the position of tumor with th help of ultrasound.
b) Bats produce ultrasound and detect the reflected sound to identify the prey or obstacle on the way.
The nature of the image formed are: real, inverted, diminished and between F and 2F.
Sound wave having frequency more than 20 kilohertz is called ultrasonic wave. Two animals that can produce an here ultrasound are bat and dolphin.
Two applications of ultrasound are:
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