Current Electricity Concise 9th Physics Selina Publishers

Chapter-9 Revised Physics Solved Questions of Exercise-9

Current Electricity Selina 9th Concise Physics Solutions  Chapter-9 Current Electricity. Step By Step Revised Concise Selina Physics Solutions of Chapter-9 Current Electricity with Exe-9(A) , MCQ 9(A), Num-9(A) , Exe-9(B), MCQ-9(B), Num-9(B), Exe-9(C), MCQ-9(C) for Class-9.  Visit official Website CISCE for detail information about ICSE Board Class-9.

Current Electricity Selina Concise 9th Physics Solutions


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Exe-9(A)

MCQ 9(A)

Num-9(A)

Exe-9(B)

MCQ-9(B)

Num-9(B)

Exe-9(C)

MCQ-9(C)

Note :-  Before Viewing Selina Concise Physics Solutions of Chapter-9 Current Electricity for ICSE Class-9 Physics. Read the whole chapter carefully and Solved all example of Chapter-9 Current Electricity for Class-9 Physics.

latest syllabus of council class 9th physics

According to latest syllabus of council class 9th physics, Law of reflection, character of image, Spherical Mirror, Ray diagram and use of spherical mirror, Type of mirror, radius of curvature, Pole, Principal Axis, Focus and Focal Length.


Exe-9(A) Current Electricity ICSE Concise 9th Physics Solutions

Question 1

Name one D.C. source and one A.C. source.

Answer 1

Source of D.C.: Cell

Source of A.C.: Mains

Question 2

Distinguish between D.C. and A.C.

Answer 2

Direct current (D.C.) is a current of constant magnitude flowing in one direction but alternating current (A.C.) is a current which reverses its magnitude and direction with time.

Question 3

What is an electric cell?

Answer 3

An electric cell is a device which converts chemical energy into electrical energy. When connected in a circuit, it acts as a source of D.C. current.

Question 4

What transformation of energy takes place when current is drawn from a cell?

Answer 4

Chemical energy changes into electrical energy.

Question 5

Name the constituents of a cell.

Answer 5

Constituents of cell: Two electrodes and an electrolyte in a vessel.

Question 6

State the two kinds of cell. Give one example of each.

Answer 6

Two kinds of cells:

(a) Primary cell: e.g. Leclanche cell

(b) Secondary cell: Lead (or acid) accumulator

Question 7

What is a primary cell? Name two such cells.

Answer 7

Primary cells are cells which provide current as a result of irreversible chemical current.

Examples: Simple Voltaic cell and Leclanche cell.

Question 8

What is a secondary cell? Name one such cell.

Answer 8

Secondary cells are cells which provide current as a result of reversible chemical reactions. It converts electrical energy into chemical energy when current is passed in it (i.e. during charging), while it converts chemical energy into electrical energy when current is drawn from it (i.e., during discharging).

Example: Lead (or acid) accumulator.

Question 9

State three differences between the primary and secondary cells.

Answer 9

Primary Cell Secondary cell
1. Chemical reaction is irreversible.

2. Only chemical energy is converted into electrical energy when current is drawn from it.

3. It cannot be recharged and its internal resistance is high.

1. Chemical reaction is reversible.

2. It converts electrical energy into chemical energy when current is passed in it (i.e., during charging), while converts chemical energy into electrical energy when current is drawn from it (i.e., during discharging).

3. It can be recharged and its internal resistance is low.

Question 10

What do you understand by the term current? State and define its S.I. unit.

Answer 10

Current is the rate of flow of charge across a cross-section. It is a scalar quantity.

Its S.I. unit is ampere (coulomb per second).

If 1 ampere current flows through a conductor, it means that 6.25 x 1018 electrons pass in 1 second across that cross-section of conductor.

Question 11

How much is the charge on an electron?

Answer 11

Charge on an electron is -1.6 x 10-19 coulomb.

Question 12

n electrons flow through a cross section of a conductor in time t. If charge on an electron is e, then write an expression for the current in the conductor.

Answer 12

icse 9th concise physic exe-9(A) Ans 12

Question 13

Name the instrument used to control the current in an electric circuit.

Answer 13

A rheostat is used to control current in an electric circuit.

Question 14

In the electric circuit shown in Fig., label the parts A, B, C, D, E, and F. State the function of each part. Show in the diagram the direction of flow of current.

electric circuit

Answer 14

A: Ammeter – It measures the current flowing through the circuit.

B: Cell – It acts as a source of direct current for the circuit.

C: Key – It is used to put the current on and off in the circuit.

D: Load – It is an appliance connected in a circuit. It may just be a resistance (e.g., bulb) or a combination of different electrical components.

E: Voltmeter – It is used to measure the potential difference between two points of a circuit.

F: Rheostat – It is used to control the current in the circuit.

Rheostate

Question 15

What is the function of a key (or switch) in an electric circuit?

Answer 15

A key or switch is used to put on or off, the current in the circuit.

Question 16

Write symbols and state functions of each of following components in an electric circuit: (i) key, (ii) cell, (iii) rheostat, (iv) ammeter and (v) voltmeter.

Answer 16

icse 9th concise physic exe-9(A) Ans 16

cell symbol

It is used to control the current in the circuit.

(iv) Ammeter :  Ammeter ; It is used to measure the current flowing through the circuit.

(v) Voltmeter:voltmeter  ; It is used to measure the potential difference between two points of a circuit.

Question 17

(a) Complete the circuit given in Fig. by inserting between the terminals  and C. an ammeter.

(b) In the diagram, mark the polarity at the terminals of ammeter and indicate clearly the direction of flow of current in the circuit when the circuit is complete.

(c) Name and state the purpose of Rh in the circuit.

rh in a circuit

Answer 17

rg a, b

(c) A rheostat is used to control the current in the circuit.

Question 18

What are conductors and insulators of electricity? Give two examples of each.

Answer 18

The substances which allow electric current to flow through them easily are called conductors. Examples: Impure water and metals.

The substances which do not allow the electric current to flow through them are called insulators. Examples: Rubber and wood.

Question 19

Select conductors of electricity from the following: Copper wire, silk thread, pure water, acidulated water, human body, glass, mercury.

Answer 19

Copper wire, acidulated water and human body and mercury.

Question 20

State two differences between a conductor and an insulator of electricity.

Answer 20

Conductors have a large number of free electrons and they offer a very small resistance in the path of current but insulators have no free electrons and they offer a very high resistance in the path of current.

Question 21

Distinguish between a closed circuit and an open circuit, with the use of suitable labelled diagrams.

Answer 21

A circuit is said to be closed when every part of it is made of a conductor and on plugging in the key or on being complete, current flows through the circuit.

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