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Gen Studies (Electricity and Magnetism)

Description: Electricity and magnetism (D)
Number of Questions: 15
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Tags: Electricity and magnetism (D) Science and Technology
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Consider the following: Assertion: Insulators do not allow the flow of current through themselves. Reason: They have no free charge carriers.

  1. If both assertion and reason are true and the reason is correct explanation of assertion.

  2. If both assertion and reason are true but reason is not a correct explanation of assertion.

  3. If assertion is true and reason is false.

  4. If both assertion and reason are false.


Correct Option: A
Explanation:

Assertion is correct. Insulators do not allow the flow of current through themselves. Therefore, insulating materials are advised to use to avoid power shock. Reason is correct. Insulators do not have free charge carriers. Insulating material reduces or prevents the transmission of heat or sound or electricity.

Consider the following statements:

  1. Ammeter is an instrument used to measure the magnetic field of an object.
  2. A voltmeter is an instrument used to measure voltage.
  3. In India, the household voltage is 440V, 50hz.

Which of the given statements is/are true?

  1. Only (1)

  2. Only (2)

  3. Only (1) & (3)

  4. Only (2) & (3)


Correct Option: B
Explanation:

Statement (1) is wrong. Ammeter is an instrument used to measure the electric current.

Statement (2) is correct. A voltmeter is an instrument used to measure voltage. Statement (3) is wrong. The household voltage in India is 220 V, 50 hz.

Consider the following: Assertion: The conductivity of a superconductor is infinite. Reason: The resistance of superconductors is zero at low temperatures.

Which of the following is correct?

  1. The assertion is false.

  2. The reason is false.

  3. Both the assertion and the reason are false.

  4. Both the assertion and the reason are true and the reason is an explanation of the assertion.


Correct Option: D
Explanation:

Conductivity is the reciprocal of resistance. The resistance of superconductors is zero at low temperatures. So, the conductivity of a superconductor is infinite.

Consider the following statements: 1. In three pin switch, the pin of live wire is made bigger in size.

  1. Electricity transmitted along power lines is at very high voltages to reduce the loss of energy.

Which of the given statements is/are incorrect?

  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither of these


Correct Option: A
Explanation:

Statement (i) is wrong. In three pin switch, the pin of earth wire is made bigger in size for the security reason. Statement (ii) is correct. Yes, to reduce the risk of loss of energy, electricity transmitted along power lines is at very high voltages.

Which of the following statements regarding BEE (Bureau of Energy Efficiency) is/are correct? (1) The 5-star power saving label contains the information of resistance power of the electrical appliance. (2) Power labeling is mandatory for frost free refrigerator, air conditioner, tubular fluorescent lamp and distribution transformer.

  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither (1) nor (2)


Correct Option: B
Explanation:

(i) Statement (1) is wrong. The 5 star power saving label contains the information regarding electrical consumption, type of equipment, capacitance, etc. (ii) Statement (2) is also correct. Power rating is made mandatory for frost free refrigerator, air conditioner, tubular fluorescent lamp and distribution transformer.

Consider the following statements:

  1. The fuse should be connected to neutral wire of appliance to get the protection against the electric shock.
  2. The fuse wires are used for household supply of electricity should have high melting point for safety purpose.

Which of the given statements is/are correct?

  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither (1) nor (2)


Correct Option: D
Explanation:

Statement (1) is wrong. Live wires carry current and our main purpose of using fuse is to break the circuit. A short circuit fault to earth or ground will bypass the neutral wire so, if the fuse were to be installed in the neutral wire, it would not operate.

Statement (2) is also wrong. A fuse is a device which is placed into an electrical circuit to prevent excessive current flowing under fault conditions. The fuse wires should have low melting point because on overloading, the wire forming the fuse element will heat up and melt (or blow) and interrupt the current flow thus preventing damage from excessive current to the remaining circuits.

Consider the following statements:

  1. In electric bells and loudspeaker, electromagnets are used.
  2. If a man moves constantly in the direction towards which his magnetic needle points, he would reach at South Pole.

Which of the given statements is/are correct?

  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither (1) nor (2)


Correct Option: A
Explanation:

Statement (1) is correct. Electromagnets are like normal magnets. The electromagnet's strength can be increased or decreased by changing the amount of electric current that flows through the magnet. Therefore, they are used in manufacturing of electric bells and loudspeakers. Statement (2) is wrong. If a man moves constantly in the direction towards which his magnetic needle points, he would reach North Pole as a freely suspended needle always points in the north direction.

If lightning strikes a moving car, and all the doors and windows of the car are closed, which of the following will happen?

  1. The persons sitting in the car will get an electric shock.

  2. The car will catch fire.

  3. The car will overturn.

  4. No effect will there.


Correct Option: D
Explanation:

Passengers inside a steel-bodied car are protected from lightning because the car behaves like a 'Faraday Cage'. When the lightning hits the car, it wants to take the shortest path with the least resistance to ground.

Consider the following statements: 1. Iron, in contact with a magnet, cannot become a magnet.

  1. Alnico is used to make magnets. Which of the given statements is/are correct?
  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither (1) nor (2)


Correct Option: B
Explanation:

Statement (1) is wrong. Iron becomes magnetised and develops the opposite pole and acts as a magnet. Statement (2) is correct. Alnico is an alloy, which consists of elements like aluminium, nickel, cobalt, copper, Iron and some other elements, which have one of the magnetic characteristics. Moreover, Alnico with these constitute elements is preferred to make magnets.

Consider the following statements:

  1. The purpose of choke in tube light is to increase the current. (2) Lightening in the sky is caused due to electric discharge produced by friction between clouds.

Which of the given statements is/are correct?

  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither (1) nor (2)


Correct Option: B
Explanation:

Statement (1) is wrong. The purpose of choke in tube light is to increase the voltage momentarily. Statement (2) is correct. Lightening in the sky is caused due to electric discharge produced by friction between clouds.

Consider the following statements:

  1. The heating of a current carrying conductor is caused due to repulsion between two opposite charged electrons.
  2. Rating is the method of connecting the metallic body of an electrical appliance to the earth with the help of a conducting wire.

Which of the given statements is/are correct?

  1. Only (1)

  2. Only (2)

  3. Both (1) and (2)

  4. Neither (1) nor (2)


Correct Option: D
Explanation:

Statement (1) is wrong. The heating of a current carrying conductor is caused due to loss of kinetic energy by electrons. Statement (2) is wrong. Earthing is the method of connecting the metallic body of an electrical appliance to the earth with the help of a conducting wire.

A child rubs a rubber ruler and then puts it near some tiny pieces of paper. The paper pieces are then attracted to the ruler. Which of the following statements best explains the result?

  1. Paper is naturally a negative material.

  2. Rubber and paper always attract each other.

  3. The paper becomes charged by induction.

  4. The paper acquires a net positive charge by induction.


Correct Option: D
Explanation:

By rubbing the rubber ruler, it acquires the negative charge. When it comes in contact with tiny piece of paper (having no charge), it induces the opposite positive charge.

Consider the following statements:

  1. In torch cell, photochemical reaction takes place.
  2. An electroencephalogram (EEG) is a test used to detect abnormalities related to electrical activity of the heart.

Which of the given statements is /are incorrect?

  1. Only (1)

  2. Only (2)

  3. Both (1) and (2)

  4. Neither (1) nor (2)


Correct Option: C
Explanation:

Statement (1) is wrong. In torch cell, electrochemical reaction takes place. Photochemical reaction occurs with the absorption of light. Statement (2) is wrong. An electroencephalogram (EEG) is a test used to detect abnormalities related to electrical activity of the brain. Electrocardiogram (ECG) is the diagnostic test for heart.

Which of the following is the principle of a traditional tape player, which is used to play music on a cassette tape?

  1. The photoelectric effect.

  2. Force acting on a current-carrying wire in a magnetic field.

  3. Induced current from the motion of the tape.

  4. Friction between the tape and the machine.


Correct Option: C
Explanation:

The magnetic imprint on the tape induces a small current in the head, which approximates the original signal and is then amplified for playback.

Consider the following statements:

  1. When a bar magnet is cut into two equal halves, the pole strength of each piece becomes doubled.
  2. The ability of a material to remain magnetized after removal of the magnetizing force is known as retentivity. Which of the given statements is/are incorrect?
  1. Only (1)

  2. Only (2)

  3. Both (1) & (2)

  4. Neither (1) nor (2)


Correct Option: A
Explanation:

Statement (1) is incorrect. When a bar magnet is cut into two equal halves, the pole strength of each piece remains the same. Each broken piece forms its own magnetic field. Statement (2) is correct. Retentivity is the capacity of a body to remain magnetized after magnetizing field has ceased to exert an effect.

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