EduRev

Courses

Get the App Signup / Login

Welcome Back

Forgot Password?

New User? Sign Up

Create your account now

I accept the Terms & Conditions.

Already Have an Account? Login

Important Questions Test: Electric Current & its Effects

20 Questions MCQ Test General Science(Prelims) by IRS Divey Sethi | Important Questions Test: Electric Current & its Effects

Description

Attempt Important Questions Test: Electric Current & its Effects | 20 questions in 20 minutes | Mock test for Class 7 preparation | Free important questions MCQ to study General Science(Prelims) by IRS Divey Sethi for Class 7 Exam | Download free PDF with solutions

QUESTION: 1

A battery consists of

A.
only one cell
B.
only two cells
C.
two or more cells
D.
All of the above

Solution:

A battery consists of some number of voltaic cells. Each cell consists of two half-cells connected in series by a conductive electrolyte containing metal cations.

QUESTION: 2

Select the one in which heating effect of current is not used.

A.
Electric iron
B.
Electric immersion heater
C.
Electric geyser
D.
A battery

Solution:

The chemical reactions in the battery causes a build up of electrons at the anode.

QUESTION: 3

When an electric current is flowing through a conductor it

A.
Experiences a force when it is in a magnetic field
B.
Experience no force when it is in a magnetic field
C.
Experiences the force only if the field is of electromagnetic nature
D.
All of the above

Solution:

Experiences a force when it is in a magnetic field

QUESTION: 4

The magnetic field around a current-carrying coil lasts

A.
for a few hours
B.
a few minutes
C.
for ever
D.
for the duration for which current flows through it

Solution:

for the duration for which current flows through it

QUESTION: 5

When electric current flows through a conductor, the conductor becomes

A.
liquid
B.
vapor
C.
hot
D.
cold

Solution:

When an electric current flows through a conductor, it becomes hot because,the resistance of the conductor blocks the electricity flow.

QUESTION: 6

By whom was magnetic effect of current discovered?

A.
Faraday
B.
Fleming
C.
Oersted
D.
None of these

Solution:

The magnetic effect of current was discovered by H.C. Oersted.

QUESTION: 7

A fuse is fixed in a circuit in order to

A.
decrease the amount of current
B.
increase the amount of current
C.
increase the power consumed in the circuit
D.
safeguard against excessive current.

Solution:

It acts as safeguard against excessive current. When the current exceeds certain limit the fuse wire gets broken and so it acts as a safeguard.

QUESTION: 8

Select the one that you will prefer to make an electromagnet.

A.
Steel
B.
Plastic
C.
Stainless steel
D.
Soft iron

Solution:

The soft iron inside the coil makes the magnetic field stronger because it becomes a magnet itself when the current is flowing. Soft iron is used because it loses its magnetism as soon as the current stops flowing. Soft iron is said to form a temporary magnet. In this way, the electromagnet can be switched on and off by turning the electricity on and off.

QUESTION: 9

Tungsten is used for the manufacture of an electric bulb because

A.
it is malleable
B.
it is inexpensive
C.
it has a very high melting point
D.
it is a good conductor

Solution:

The metal tungsten is used for the filaments in incandescent bulbs. It has a high melting point and retains its strength when heated. The tungsten's resistance makes it glow white-hot, and inert gases (mostly nitrogen) in the bulbs keep the tungsten from oxidizing.

QUESTION: 10

In an electric motor, conversion takes place of

A.
chemical energy into electrical energy
B.
electrical energy into mechanical energy
C.
electrical energy into light
D.
electrical energy into chemical energy

Solution:

electrical energy into mechanical energy

QUESTION: 11

Key or switch in circuit is placed:

A.
left side of the battery
B.
right side of the battery
C.
any where in the circuit
D.
near the positive terminal of the bulb

Solution:

The key or switch can be placed anywhere in the circuit. When the switch is in the 'ON' position, the circuit from the positive terminal of the battery to the negative terminal is complete.

QUESTION: 12

In which circuit will the bulb or bulbs glow the brightest?

A.
A simple circuit with one bulb and one cell
B.
A simple circuit with one bulb and two cells
C.
A simple circuit with two bulbs and one cell
D.
A simple circuit with two bulbs and two cells

Solution:

The chemical energy stored in two cells is more than one. The electrical energy used by one bulb is less than the energy used by two bulbs. So the bulb in the circuit that has one bulb and two cells will glow the brightest.

QUESTION: 13

Which of the following instruments is used to check whether electricity is flowing through a substance or not?

A.
Voltmeter
B.
Ammeter
C.
Tester
D.
Cell

Solution:

Tester is used to check whether electricity is flowing through a substance.

QUESTION: 14

Why are symbols used for electronic components?

A.
It makes it easier to draw the circuit diagrams
B.
It is essential to draw the circuit diagrams
C.
It helps to show the direction of flow of current in a circuit
D.
All of the above

Solution:

It makes it easier to draw the circuit diagrams

QUESTION: 15

The acting contacts for circuit breakers are made of

A.
Stainless steel
B.
Hard pressed carbon
C.
Porcelain
D.
Copper tungsten alloy

Solution:

Copper tungsten materials are often used for arcing contacts in medium to high voltage sulfur circuit breakers in environments that can reach temperatures above 20,000K.

QUESTION: 16

The primary cell which is used in daily life is

A.
Leclanche cell
B.
Dry cell
C.
Daniel cell
D.
Simple voltaic cell

Solution:

Dry cells are more durable, they are typically used for remote controls, flashlights and other similar handheld devices.

QUESTION: 17

Electric current is measured by a device called

A.
Voltmeter
B.
Ammeter
C.
Electroscope
D.
None of these

Solution:

An ammeter is an instrument used for measuring electric current in units of amperes. An ammeter must be connected in series with the path of the current being measured.

QUESTION: 18

When electricity is passed through a coil

A.
Magnetic field is produced
B.
Heat is developed in the coil
C.
Energy is lost in the form of heat
D.
All the above

Solution:

When an electric current is passed through the wire of the coil to generate a magnetic field, or conversely an external time-varying magnetic field through the interior of the coil generator and energy is also lost in the form of heat.

QUESTION: 19

Study of relationship between electricity and magnetism is called

A.
Current electricity
B.
Electric magnetism
C.
Magneto electricity
D.
Electromagnetism

Solution:

Electromagnetism is a branch of Physics, deals with the electromagnetic force that occurs between electrically charged particles.

QUESTION: 20

What is the material for electric fuse?

A.
Cu
B.
Constantan
C.
Tin-lead alloy
D.
Nichrome

Solution:

The material mainly used for fuse element are tin, lead, silver, copper, zinc and alloy of lead and tin. An alloy of lead and tin is used for small current rating fuses