Electricity and Magnetism Test

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Electricity and Magnetism Test - 5

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Question 1
1 / -0

A glass rod rubbed with silk is brought near the cap of a negatively charged gold leaf electroscope. The leaf divergence will

A
decrease

B
increase

C
remain unchanged

D
first increase, then decrease

Solution

When glass rod is rubbed with silk,glass rod will acquire positive charge. When positive charge is brought near negatively charge electroscope, repulsion between leaves of electroscope will decrease and thus divergence will decrease.
Question 2
1 / -0

If 18.75 10¹⁸ electrons flow through a conductor in 3 seconds, the total charge that flows through the conductor is

A
1 C

B
2 C

C
3 C

D
4 C

Solution

The answer is 18.75 x 10¹⁸ x 1.6 x 10^-19 C = 3 C
Thus, answer option 3 is correct.
Question 3
1 / -0

If the current in a household appliance is 6.00 A, what amount of charge passes through the appliance in 15.0 s?

A
2.5 C

B
90.0 C

C
40.0 C

D
45.0 C
Question 4
1 / -0

There is no flow of current between two charged bodies when connected because

A
they have the same quantity of charge

B
they are at the same potential

C
they have the same capacity

D
they have the same ratio of potential per unit charge
Question 5
1 / -0

A cell is connected to a bulb which develops a potential difference of 16 volts across it. The current in the circuit is measured to be 2 amperes. What is the resistance offered by the filament of the bulb to the flow of current?

A
32

B
16

C
2

D
8
Question 6
1 / -0

The V-I graph of two metallic wires A and B is shown below. Which of them has a greater resistance?

A
A

B
B

C
Both have the same resistance

D
Cannot be determined
Question 7
1 / -0

A wire has a resistance `R` and resistivity . What will be its resistivity, if its length is tripled and area is halved?

A

B
6

C
/6

D
Question 8
1 / -0

Resistance of a metallic wire of length `` and area of cross-section `A` is `R`. If the diameter of the wire is doubled, keeping the length unchanged, what will be the new resistance of the wire?

A

B
2R

C

D
4R
Question 9
1 / -0

When the main switch of the house circuit is put off, it disconnects the

A
live wire

B
neutral wire

C
earth wire

D
live and neutral wires
Question 10
1 / -0

Tungsten is mainly used for making filaments of electric bulbs because of its

A
low cost

B
high melting point

C
high electrical conductivity

D
low thermal conductivity
Question 11
1 / -0

An electric iron consumes energy at a rate of 720 W when heating is at the maximum rate and 340 W when the heating is at the minimum. If the voltage is 220 V, what is the resistance in each case?

A
3.3 , 1.5

B
67.2 , 142.4

C
158.4 , 748.0

D
2356.4, 525.5

Solution

R = V²/P where R is the resistance in Ohms, V is the voltage in Volts and P is the power in Watts.
Plugging in the values, we get the values of resistances as 67.2 ohms and 142.4 ohms.
Thus, answer option 2 is correct.
Question 12
1 / -0

If 200 J of heat is produced every second in a 2 resistance, what is the potential difference across the resistor?

A
20 V

B
50 V

C
25 V

D
100 V
Question 13
1 / -0

An electric refrigerator rated 400 W operates 6 hours per day. What is the cost of the energy to operate it for 30 days at Rs. 3.00 per kWh?

A
Rs. 240.00

B
Rs. 600.00

C
Rs. 216.00

D
Rs. 135.00
Question 14
1 / -0

How much energy is used when a 110 kW appliance is used for 120 minutes?

A
110 kWh

B
132 kWh

C
220 kWh

D
120 kWh
Question 15
1 / -0

When a bar magnet immersed in a heap of iron fillings is taken out, it is observed that iron fillings stick to the surface of the bar magnet. The iron fillings would

A
stick uniformly throughout the surface of the bar magnet

B
stick randomly on the surface of bar magnet

C
have maximum concentration at the two ends of the bar magnet

D
have maximum concentration slightly away from the two ends of the bar magnet
Question 16
1 / -0

Which of the following statements are true about a permanent magnet?
(i) It is made up of steel.
(ii) It produces a permanent magnetic field.
(iii) The magnetic field strength of a permanent magnet can be changed.
(iv) It can be easily demagnetised.
(v) The permanent magnets are not so strong.

A
Only (i), (ii) and (v)

B
Only (i) and (ii)

C
Only (i), (ii), (iv) and (v)

D
Only (i), (ii) and (iv)
Question 17
1 / -0

What happens when a conductor is placed in a magnetic field such that the current in it is in the direction parallel to the direction of magnetic field?

A
No force acts on the conductor

B
Maximum force acts on the conductor

C
Conductor experiences rotation

D
Both (2) and (3)
Question 18
1 / -0

Which of the following phenomenon is used to generate electricity in generators?

A
Electrolysis

B
Electromagnet conduction

C
Electromagnetic induction

D
Electro spectrometry
Question 19
1 / -0

As illustrated below, moving a magnet towards a coil sets up a current in the coil circuit, as indicated by deflection in the galvanometer needle.

Which of the following statements is NOT true?

A
Faster the movement, higher is the current.

B
Changing the direction of the movement,changes the direction of the current.

C
Stronger the magnet, higher is the current.

D
More the number of coils of wire, lower is the current.
Question 20
1 / -0

Which of the following statements is NOT true?

A
A magnet can induce a current.

B
The flux can be changed by moving a magnet near a coil or moving a coil near a magnet.

C
When the magnetic flux linked with a circuit changes, an emf is induced in the circuit.

D
The phenomenon of electromagnetic induction is used to change electrical energy to mechanical energy in electric motors.