# NCERT Science Class 10 Chapter 16 Electricity CBSE Board Sample Problems Very Short Answer (For CBSE, ICSE, IAS, NET, NRA 2023)

Get top class preparation for CBSE/Class-10 right from your home: get questions, notes, tests, video lectures and more- for all subjects of CBSE/Class-10.

## Question

Why is tungsten metal used in bulbs but not in fuse wires?

### Solution

• ANS-It is because tungsten has a very high melting point.
• If it is used as a fuse wire, then it will not melt even when large amount of current is passed through it, and the appliance will be damaged

## Question

Why are copper wires used as connecting wires?

### Solution

The electrical resistivity of copper is low.

## Question

(1) By what other name is the unit joule/coulomb called?

Volt

## Question

Nichrome is used to make the element of an electric heater why?

### Solution

Nichrome is an alloy of high resistivity and high melting point and does not oxidise easily

## Question

Name the instrument used to measure

(i) Electric current in a circuit,

(ii) Potential difference between two points in a circuit

(i) Ammeter,

(ii) Voltmeter

## Question

State Ohm՚s Law

### Solution

According to Ohm՚s Law at constant temperature and pressure, the current passing through a conductor is directly proportional to the potential difference across its end, i.e..

## Question

When do we say that the potential difference between two points of a circuit in 1 voIt

### Solution

Potential difference between two points of an electric circuit is said to be 1 volt when a work of 1 J is to be done for moving a charge of 1 C between two points.

## Question

What happens to the resistance of a conductor when temperature is increased?

### Solution

The resistance of a conductor increase with rise in temperature. As R ci T.

## Question

Why is tungsten used for making filament of electrical bulbs?

### Solution

Because tungsten has high melting point and high (resistivity) .

## Question

Why do we prefer using copper and aluminium for transmission of electric current?

### Solution

Because of their low resistivity/cost.

## Question

Two bulbs having power of 50 w and 25 w respectively are connected with the same source. Which has higher resistance?

What is their ratio?

### Solution

i.e., 50 W bulb has resistance than 25 W.

## Question

A wire of resistance 5 is bent in the form of a closed circle.

Find the resistance across the diameter of the circle?

### Solution

R = 5

Consider two semicircular elements connected across the diameter.

Total resistance is 5

Resistance of two semicircular elements is

Both the elements are connected in parallel.

## Question

List any two factors on which resistance of a wire depends on.

### Solution

Resistance depends on:

Length of wire (directly proportional)

Cross-sectional area (inversely proportional)

## Question

The electric power consumed by a device may be calculated by either of the two expressions or . the first expression indicates that it is directly proportional to R whereas the second expression indicates inverse proportionality. How can the seemingly different dependence of P on R in these expressions be explained? (1)

### Solution

is used to calculate electric power when the current flowing through the circuit is constant (Series combination) .

is used to calculate electric power when the potential difference flowing through the circuit is constant (Parallel combination) .