Electric Current and its Effects Test

Result

Electric Current and its Effects Test - 5

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following materials should be used to make the coil of an electromagnet in order to increase its strength?

A
Plastic

B
Copper

C
Iron

D
All of the above

Solution

Copper is a good conductor of electricity, so it should be used for the coil of an electromagnet in order to increase its strength.
Question 2
1 / -0

What is the difference between the wires used in the elements of an electric heater and a fuse?

A
The resistivity of the wire used in a heater element is high, while a fuse wire has low resistivity.

B
The resistivity of the wire used in a heater element is low, while a fuse wire has high resistivity.

C
The melting point of the wire used in a heater element is high, while a fuse wire has low melting point.

D
The melting point of the wire used in a heater element is low, while a fuse wire has high melting point.

Solution

A fuse wire should have high resistivity and low melting point as fuse melts down to protect the electrical appliances by breaking the circuit when current more than the permissible value passes through it. The wire used in a heater element has high resistivity and high melting point as the heat produced in the element due to large resistivity (hence large resistance) is used to heat the water.
Question 3
1 / -0

If 18.75 × 10¹⁹ electrons flow through a conductor in 3 seconds, the total charge that flows through the conductor is

A
10 C

B
20 C

C
30 C

D
40 C

Solution

Total charge flown (Q) = number of electrons(n) × charge on the one electron (e)
Q = ne
Q = 18.75 × 10¹⁹ × 1.6 × 10^-19
Q = 30 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

Solution

Current will flow only if there is a potential difference between two points.

That is, there is no flow of current between two charged bodies when connected because they are at the same potential.
Question 5
1 / -0

The minimum number of cells required to make a battery is

A
1

B
2

C
4

D
6

E
10

Solution

A battery is a combination of cells connected together. The positive terminal of one cell is connected to the negative terminal of the next cell. The minimum number of cells needed to make a battery is 2.
Question 6
1 / -0

A current of 3.2 A is flowing through a conductor. The number of electrons flowing per second is

A
51.2 × 10¹⁹

B
5.12 × 10²⁴

C
3.2 × 10¹⁹

D
2 × 10¹⁹

Solution

Current (I) = Charge (q)/Time (t)

Charge = Number of electrons (n) × Charge on one electron (e)

The number of electrons flowing per second
Question 7
1 / -0

Directions For Questions

Directions: Read the paragraph given below and answer the following question.
An electric source powers the electromagnet used in an electric bell. The switch which you press to sound an electric bell acts as the circuit breaker or the switch which completes the circuit.
When the switch (K) is pressed, the circuit loop is complete, which causes current to flow through the circuit. The arm (A) which strikes the gong (B) is connected to a spring (T) at one end and an iron ball at the other end. This is called a clapper or a striker. The arm is attached to an iron strip (I) which is attracted to the electromagnet (E) when the circuit is complete and current is flowing through it.
This is because the magnetic field created by the electromagnet attracts the iron strip towards it when the circuit is complete.

...view full instructions

What will happen if an iron strip is replaced by a glass strip?

A
The bell will start ringing louder.

B
The bell will not ring at all.

C
The strip will remain attached to the electromagnet.

D
Sometimes the bell will ring, sometimes it will not ring.

Solution

As the glass is not a magnetic material, it will not be attracted by the electromagnet. Hence, the bell will not ring.
Question 8
1 / -0

Moving a small charge of 1.6 10^-19 C between two parallel plates increases its electric potential energy by 4.8 10^-16 J. What is the electric potential difference between the two parallel plates?

A
3 10³ V

B
4 10⁴ V

C
5 10⁴ V

D
6 10³ V

Solution

V = = 4.8 10^-16/1.6 10^-19= 3 10³ V
Question 9
1 / -0

In an electric circuit, the amount of electric charge flowing through an electric bulb, in 5 minutes is 100 C. What will be the magnitude of electric current through the filament?

A
2.33 A

B
1.33 A

C
0.33 A

D
0.23 A

Solution
Question 10
1 / -0

Which of the following statements is/are incorrect?

(a) An electric bell is an application of electromagnets.
(b) Heating effect of current is used in an electric bell.
(c) The coil in a bell behaves like a magnet when no current flows through it.

A
Only (a)

B
Only (b) and (c)

C
Only (a) and (c)

D
Only (a) and (b)

Solution

Heating effect of current is used in heaters and not in a bell, which works on the principle of an electromagnet. The coil in a bell stops behaving like a magnet when no current flows through it.
Question 11
1 / -0

In which of the following is an electromagnet used?

A
Electric bells

B
Loudspeaker

C
Cranes to pick up cars

D
All of these

Solution

When a soft iron bar is placed inside a solenoid carrying current, it becomes a magnet as long as current flows through the solenoid. Such a magnet is known as an electromagnet. They are used to lift heavy iron pieces. They are fitted on cranes, which lift heavy masses of scrap iron.
They are also used in many devices, like electric bell, electric horn, telephone receiver, electric relay, microphones, television, loudspeakers, etc. Hence, option (4) is correct.
Question 12
1 / -0

Why does a wire through which current flows attract iron pieces?

A
Because the wire gets overheated

B
Because the wire breaks the circuit and melts

C
Because the current-carrying wire behaves like a magnet

D
Because the wire is made of conductive material

Solution

A wire through which current flows attracts iron pieces because the wire possesses magnetic force of attraction like a magnet.
Question 13
1 / -0

A current of 4 amperes flows through a conductor. Q is 1600 coulombs. For how long does the current flow?

A
2 min and 40 seconds

B
6 min and 40 seconds

C
12 min

D
20 min

Solution

Current (I) = Charge (Q)/Time (t)

Or, t = 6 min and 40 sec
Question 14
1 / -0

What is the value of charge when work done is 1760 joules and potential difference is 220 volts?

A
4 C

B
6 C

C
7 C

D
8 C

Solution

Potential difference (V) = Work done (W)/Charge (Q)

Q = W/V

V = 220 volts, W = 1760 joules

Q =

Q = 8 C
Question 15
1 / -0

Four cells, each of voltage `V` across them, are joined in parallel to form a battery. What will be the equivalent voltage of the battery?

A
V/4

B
4V

C
V

D
Zero

E
None of these

Solution

As the four cells are connected in parallel, the voltage remains the same whatever is the number of cells connected.
Hence, the equivalent voltage will be V.