Electricity
Choose the best alternative:
1. The unit of resistivity is
a) Ohm b) Ohm/m c) Ohm×m d)
Ampere
2. If a wire is stretched to
make its length three times, its resistance will become
a) Three-times b) One-third c) One-Ninth d)
Nine-times
3. Instrument used to measure
electric current
a) Voltmeter b) Ammeter c) Cell d) Nichrome
4. What is the SI unit of
potential difference?
a) Ampere b) Volt c) Ohm d)
None of these
5. Electromotive force is
measured in
a) Joule b) Coulomb c) Volt d)
Ohm
6. Which of the following has
low resistivity?
a) Nichrome b) Maganin c) Constantan d)
Copper
- What is the SI unit of electric charge?
a)
Ampere b)
Coulomb c) Volt
d) Ohm
- Electric current (I) is mathematically defined as:
a)
I=V×R b)
I=Q/t c)
I=W/Q d) I=P×t
- Which instrument is used to measure electric current in a circuit?
a)
Voltmeter b) Photometer
c) Ammeter d)
Ohmmeter
- How is an ammeter connected in an electric circuit?
a) In a series combination b)
In a parallel combination
c)
Across the load only d)
It can be connected any way
- What is the value of 1 milliampere (mA)?
a)
10−6 A b)
103 A c)
10−3 A d) 10−2 A
- The amount of energy transformed when a unit charge flows from one
point to another is known as:
a) Electromotive force b)
Potential difference (voltage)
c)
Resistance d)
Power
- Which instrument is used to measure potential difference and is
connected in parallel to the load?
a)
Ammeter b)
Voltmeter c)
Galvanometer d) Multimeter
- According to Ohm’s law, current is directly proportional to:
a)
Resistance b) Time c) Potential
difference d) Electric charge
- What is the SI unit of electrical resistance?
a)
Coulomb b) Watt c) Ohm (Ω) d)
Joule
- Which of the following factors increases the resistance of a
conductor?
a)
Decreasing temperature b)
Increasing length
c)
Increasing cross-sectional area d)
Using a thicker wire
- In which type of combination is there only one path for the current
to flow?
a)
Parallel combination b)
Series combination
c)
Mixed combination d)
Open circuit
- The total resistance (R) of three resistors joined in a series
combination is:
a)
1/R=1/R1 +1/R2 +1/R3 b) R=R1 +R2 +R3
c)
R=V/I d)
R=R1 ×R2 ×R3
- In a parallel combination of resistors, the total current in the
circuit:
a) Decreases b)
Increases c) Remains
the same d) Drops to zero
- Which substance is commonly used to make the heating coil of an
electric heater?
a)
Tungsten b) Copper c) Nichrome
d)
Aluminium
- What material is used for the filament in a light bulb to convert
electrical energy into light?
a)
Nichrome b)
Tungsten c)
Carbon d) Silver
- Electric power (P) can be calculated using the formula:
a)
P=V/I b) P=I/V
c) P=V×I
d) P=V×R
- What is the commercial unit of electricity consumption?
a)
Joule b)
Kilowatt-hour c) Watt-second d) Ampere-hour
- One unit of electricity (1 kWh) is equal to how many Joules?
a)
3.6×105 J b)
6.3×106 J c)
3.6×106 J d) 360 J
- The primary cause of potential difference in a circuit is:
a)
Resistance b)
Electromotive force (e.m.f.)
c)
Current flow d)
Heating effect
- Which device is used in a domestic circuit to measure the amount of
transformed electrical energy for billing?
- a) Voltmeter b)
Electric meter c)
Ammeter d) Transformer
Very short answer type questions:
1.
Define one ampere of current.
An ampere is defined as the flow of one
coulomb of electric charge in one second.
2.
What is electromotive force of
a cell?
The electromotive force (emf) is the total
amount of electrical energy provided by the source (such as a cell or
battery) to each coulomb of charge so that it can flow through the entire
circuit.
3.
Define potential difference.
Potential difference is the amount of energy transformed when a unit charge flows
from one specific point in a circuit to another.
4.
What is the unit of electric
power consumption?
The commercial unit for measuring electricity
consumption is the kilowatt-hour (kWh).
5.
Define resistor.
A resistor is an electrical load or component
that provides obstruction to the flow of electric charges.
6.
Define heating effect of
electricity.
The heating effect of electric current is the
process by which electrical energy is converted into heat energy as it passes
through an electric load with resistance.
7.
Define series combination of
electric load.
8.
A series combination is a circuit arrangement
where resistors or electric loads are joined end-to-end such that there is only
one path for the current to flow, through every load.
9.
What is the SI unit of electric
charge?
The SI unit of electric charge is the coulomb (C).
10.
Write the mathematical formula
for electric current.
Electric current (I) is given by I = Q/t, where
Q=charge and t= time.
11.
What is the SI unit of electric
current?
The SI unit of electric current is the ampere (A).
12.
4. How many amperes are equivalent to 1
milliampere (mA)?
1×10-3 A is equivalent to 1 mA.
13.
Which instrument is used to
measure current in a circuit?
An ammeter is used to measure the electric
current.
14.
How should an ammeter be
connected in a circuit?
An ammeter must be connected in a series
combination in a circuit.
15.
What is potential difference
(voltage)?
Potential difference is the amount of energy
transformed when a unit charge flows from one point of a circuit to another.
16.
What is the SI unit of
potential difference?
The SI unit of potential is the volt (V).
17.
Which instrument measures
potential difference and how is it connected?
A voltmeter is used, and it is connected parallel
to the load.
18.
State the mathematical
relationship of Ohm’s law.
The relationship is expressed as (where is
potential difference, is current, and is resistance).
19.
What is the SI unit of
electrical resistance?
The SI unit of resistance is the ohm (Ω).
20.
How does the length of a
conductor affect its resistance?
Increasing the length of a conducting wire increases
its resistance.
21.
What is a series combination of
resistors?
It is a circuit where resistors are joined
end-to-end so there is only one path for current to flow.
22.
Write the formula for total
resistance in a series circuit.
The total resistance () is the sum of individual
resistances: .
23.
In which combination does the
potential difference remain the same across all resistors?
The potential difference remains the same in a parallel
combination.
24.
Why is nichrome wire used in
electric heaters?
It is used because it has a high melting point
and does not oxidize easily at high temperatures.
25.
Which material is used for the
filament in a light bulb?
Tungsten wire is used
because it converts electrical energy into heat and light.
26.
Write the formula for electric
power in terms of voltage and current.
Electric power (P) is calculated as : P = V× I
27.
19. What is the commercial unit of electricity
consumption?
The commercial unit is the kilowatt-hour (kWh),
which is simply called a "unit".
28.
20. How many Joules are in 1 kilowatt-hour (1
kWh)?
There are 3.6 ×106 Joule in 1 kilowatt-hour(Kwh).
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