Test: Electric Current And Its Effects - 3


20 Questions MCQ Test Science Class 7 | Test: Electric Current And Its Effects - 3


Description
This mock test of Test: Electric Current And Its Effects - 3 for Class 7 helps you for every Class 7 entrance exam. This contains 20 Multiple Choice Questions for Class 7 Test: Electric Current And Its Effects - 3 (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Electric Current And Its Effects - 3 quiz give you a good mix of easy questions and tough questions. Class 7 students definitely take this Test: Electric Current And Its Effects - 3 exercise for a better result in the exam. You can find other Test: Electric Current And Its Effects - 3 extra questions, long questions & short questions for Class 7 on EduRev as well by searching above.
QUESTION: 1

A battery consists of

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.

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

Solution:

Experiences a force when it is in a magnetic field

QUESTION: 4

The magnetic field around a current-carrying coil lasts

Solution:

for the duration for which current flows through it

QUESTION: 5

When electric current flows through a conductor, the conductor becomes

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?

Solution:

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

QUESTION: 7

A fuse is fixed in a circuit in order to

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.

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

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

Solution:

electrical energy into mechanical energy

QUESTION: 11

Key or switch in circuit is placed:

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?

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?

Solution:

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

QUESTION: 14

Why are symbols used for electronic components?

Solution:

It makes it easier to draw the circuit diagrams

QUESTION: 15

The acting contacts for circuit breakers are made of

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

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

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

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

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?

Solution:

Fuse wire is made of a tin-lead alloy and not copper because they have high resistance due to high resistance the wire heats up quickly, when large current flows.They have low melting point which melts and breaks off the circuit.