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Electricity

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Consider a parallel circuit with 10 cells each in 5 rows with emf 1.5 volt and resistance 1 Ω, where there is an external resistance of 20 Ω. Calculate the current.

  1. 0.166 amp

  2. 0.434 amp

  3. 230 amp

  4. 330 amp

  5. 0.68 amp


Correct Option: E
Explanation:

Number of cells in a row n = 10 Number of such rows m = 5 i = nE/(R + nr/m) = 10 x 1.5/(20 + 10 x 1/5) = 15/22 = 0.68 amp

Calculate the amount of electric charge that flows through the circuit with a current of 0.5 A in 5 minutes.

  1. 1.6 x 10-3 C

  2. 150 C

  3. 600 C

  4. 10 C

  5. 2.5 C


Correct Option: B
Explanation:

I = 0.5 A; t = 5 minutes = 300 s Q = It = 0.5 A × 300 s = 150 C

In series grouping, the anode of one cell is connected to the cathode of another cell. Which of the following properties is not related to n identical cells connected in series?

  1. P = (nE/R + nr)2 x R

  2. Req = r/n

  3. Eeq = nE

  4. i = nE/R + nr

  5. V = iR


Correct Option: B
Explanation:

Equivalent internal resistance Req = r/n It is for n identical cells connected in parallel. 

Calculate the current when heating is at the maximum rate of an electric device, which consumes energy at a rate of 600 W, where the voltage is 220 V.

  1. 0.366 A

  2. 2.72 A

  3. 80.66 A

  4. 0.012 A

  5. 1636.3 A


Correct Option: B
Explanation:

When heating is at the maximum rate, the current I = P/V I = 600 W/220 V = 2.72 A

Which of the following devices is used to measure the potential difference across a conductor?

  1. Wattmeter

  2. Voltmeter

  3. Ammeter

  4. Galvanometer

  5. Thermometer


Correct Option: B
Explanation:

A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit.

Calculate the value in unit of the commercial unit of electric energy, which is kilowatt hour (kW h),

  1. 3.6 × 106 joule

  2. 0.277 joule

  3. 16.66 joule

  4. 60000 joule

  5. 6000 joule


Correct Option: A
Explanation:

1 kW h = 1000 watt × 3600 second = 3.6 × 106 watt second = 3.6 × 106 joule (J)

Which of the following represents the case in which electric charge does not move?

  1. Current electricity

  2. Conductor

  3. Static electricity

  4. Electric potential

  5. Potential difference


Correct Option: C
Explanation:

Static electricity:The electric charge in it does not move.

If electrons move around the nucleus of radius 5 × 10–11m and time period is 1.5 × 10–16s, what is the current?

  1. 2.4 x 10-35 A

  2. 0.937 x 103 A

  3. 1.07 x 10-3 A

  4. 0.585 x 1022 A

  5. 1.70 x 10-22 A


Correct Option: C
Explanation:

i = q/t = 1.6 x 10-19/1.5 x 10-16 = 1.07 x 10-3 A

Which of the following factors is essential in measuring the potential difference by an instrument?

  1. Instrument having a low resistance.

  2. Voltmeter is always connected in parallel across the points.

  3. We use an ammeter to measure the potential difference.

  4. The potential difference across the inductor increases.

  5. The potential difference across the resistor is not zero.


Correct Option: B
Explanation:

It is always connected in parallel across the points where the potential difference is measured.

If 5 V battery consists of a charge coulomb passing through it, then calculate the energy.

  1. 8 x 10-19 C

  2. 3.12 x 1019 C

  3. 15.62 x 1019 C

  4. 40 x 10-19 C

  5. 0.32 x 10-19 C


Correct Option: A
Explanation:

V = 5 V, Q = 1.6 x 10-19 C W = VQ W = 5 x 1.6 x 10-19  W = 8 x 10-19 C

Which of the following factors does not affect the resistance of a conductor?

  1. Effect of length of a conductor

  2. Effect of area of cross section of a conductor

  3. Effect of nature of material of a conductor

  4. Effect of temperature

  5. Effect of pressure


Correct Option: A
Explanation:

On increasing the length of the wire, its resistance increases and vice-versa. Conductance is proportional to the amount of flow under a given pressure.

Which of the following formulas is used for heat produced in a wire?

  1. I2 x R x t

  2. I x t

  3. V x I

  4. V x I x t

  5. W/t


Correct Option: A
Explanation:

It is clear that the heat produced in a wire is directly proportional to the square of current, resistance of wire and time for which the current is made to flow.

Why is the parallel electric circuit better for connecting bulbs in a house?

  1. The overall resistance of the circuit increases too much.

  2. Electrical appliance gets the same voltage.

  3. Electrical appliances have only one switch.

  4. If one electrical appliance stops working, then the others also stop working.

  5. They have a single operation.


Correct Option: B
Explanation:

In parallel circuits, each electrical appliance gets the same voltage as that of the power supply line.

Which of the following applications is not suitable for the heating effect of current?

  1. Electric fuse

  2. CFL's

  3. Electric bulb

  4. Electric iron

  5. Water geysers


Correct Option: B
Explanation:

CFL's do not depend on the heating effect of electricity to produce light, since they do not use filaments.

Which of the following formulas is used for power in terms of I and R?

  1. P = IR

  2. P = I2/R

  3. P = I2R

  4. P = I/R

  5. P = R/I2


Correct Option: C
Explanation:

We have, P = v x I Now from ohm’s law, we have V/I = R Or v = I X R , now from 1 P = I2R where  I = current and R = resistance

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