Electric Current — Practice

Question 1

A uniform wire of resistance 50 ohm is cut into five equal parts. These parts are now connected in parallel. The equivalent resistance of the combination is

Accepted Answer

2 ohm

Question 2

A charge is moved from point A to point B. The work done to move unit charge during this process is called

Accepted Answer

potential difference between A and B

Question 3

Joule per coulomb is the same as

Accepted Answer

1 volt

Question 4

Resistors of 2 ohm, 4 ohm and 6 ohm are connected in series. The equivalent resistance in the circuit is

Accepted Answer

12 ohm

Question 5

Resistors of 3 ohm, 6 ohm and 18 ohm are connected in parallel. The equivalent resistance in the circuit is

Accepted Answer

1.8 ohm

Question 6

Two resistors of 6 ohm each are connected in series, and this combination is connected in parallel with 12 ohm. The equivalent resistance of the circuit is

Accepted Answer

6 ohm

Question 7

The current in a wire depends

Accepted Answer

on both of them

Question 8

If the resistance of your body is 1,00,000 ohm, what current flows in your body when you touch the terminals of a 12 V battery?

Accepted Answer

0.00012 A, or 0.12 mA.

Question 9

Two bulbs have ratings 100 W, 220 V and 60 W, 220 V. Which one has the greater resistance?

Accepted Answer

The 60 W bulb.

Question 10

Are the head lights of a car connected in series or in parallel? Why?

Accepted Answer

In parallel.

Question 11

Why do we consider tungsten a suitable material for making the filament of a bulb?

Accepted Answer

Because it has a high resistivity, so it heats strongly for a given current, and a very high melting point of 3422 degrees Celsius, so it can be heated to incandescence without melting.

Question 12

Write the difference between potential difference and emf.

Accepted Answer

Potential difference is the work done by the ELECTRIC force on unit positive charge in moving it between two points in a conductor. emf is the work done by the CHEMICAL force on unit positive charge in moving it from the negative terminal to the positive terminal inside the battery.

Question 13

A house has 3 tube lights, two fans and a television. Each tube light draws 40 W, each fan 80 W and the television 60 W. On average the tube lights are on for five hours, the two fans for 12 hours and the television for five hours every day. Find the cost of electric energy used in 30 days at Rs 3.00 per kWh.

Accepted Answer

Rs 253.80.

Question 14

You have three resistors of 30 ohm each. How many different resultant resistances can be obtained by connecting them in different ways?

Accepted Answer

Four: 90 ohm (all three in series), 10 ohm (all three in parallel), 45 ohm (two in parallel, that pair in series with the third) and 20 ohm (two in series, that pair in parallel with the third).

Question 15

How can you verify that the resistance of a conductor is temperature dependent?

Accepted Answer

Measure the resistance of a bulb filament with a multimeter set to the 20 kilo-ohm range while the bulb is out of circuit. Then connect the bulb in a circuit with a battery and a key, close the key and let it glow for a few minutes, and measure the resistance again. The second reading is higher, and the only thing that has changed is the temperature of the filament.

Question 16

Explain overloading of a household circuit and why we use fuses.

Accepted Answer

All household appliances are connected in parallel between two line wires at about 240 V, so each draws its own current and the total drawn from the mains is their sum. The domestic meter is rated 5 to 20 A, so drawing more than 20 A causes overheating of the wiring and may cause a fire - this is overloading. A fuse is a thin wire of low melting point placed so that all the mains current passes through it. When the current exceeds the limit the fuse wire heats and melts, the circuit opens, and the appliances and wiring are saved.

Practice — Electric Current

Sign in to save attempts to your dashboard and track your accuracy over time

Find a verified tutor

Join a live course

Browse coaching centres

About

Categories

Support

Documentation

Get Study Tips & Updates

Download Our App

Download for iOS

Download for Android

Popular Cities