English Medium कक्षा १० - CBSE Important Questions

A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.

While performing the experiment to trace the path of a ray of light passing through a glass prism, four students marked the incident ray and the emergent ray in their diagrams in the manner shown below. 

(A) I

(B) II

(C) III

(D) IV

In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray: 

(A) is parallel to the incident ray

(B) perpendicular to the incident ray

(C) is parallel to the refracted ray

(D) bends at an angle to the direction of incident ray

Differentiate between a glass slab and a glass prism.

Answer the following question.
An electric lamp of resistance 20 Ω and a conductor of resistance 4 0 are connected to a 6 V battery as shown in the circuit. Calculate: 

(a) the total resistance of the circuit,  

(b) the current through the circuit, 

(c) the potential difference across the  (i) electric lamp and (ii) conductor, and

(d) power of the lamp.

Answer the following question.
While studying the dependence of potential difference ( V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and t. He got a straight line graph passing through the origin. What does the straight-line signify? Write the method of determining the resistance of the resister using this graph. 

At the time of short circuit, the electric current in the circuit ______.

Two bulbs of 100 W and 40 W are connected in series. The current through the 100 W bulb is 1 A. The current through the 40 W bulb will be ______.

Write the mathematical expression for Joule’s law of heating.

Compute the heat generated while transferring 96000 coulombs of charge in two hours through a potential difference of 40 V.

The resistance of a wire of 0.01 cm radius is 10 Ω. If the resistivity of the wire is 50 × 10^-8 Ω, find the length of this wire.

What is the meaning of electric power of an electrical device? Write its SI unit.

An electric kettle of 2 kW is used for 2h. Calculate the energy consumed in 

1. kilowatt hour and
2. joules.

A student wants to use an electric heater, an electric bulb and an electric fan simultaneously.

How should these gadgets be connected with the mains? Justify your answer giving three reasons.

What is meant by resistance of a conductor ? Define its SI unit.

How will the resistance of a wire be affected if its

1. length is doubled, and
2. radius is also doubled ?

Give justification for your answer.

The resistance of a resistor is reduced to half of its initial value. If other parameters of the electrical circuit remain unaltered, the amount of heat produced in the resistor will become ______.

As shown in the diagram an aluminium rod 'AB' is suspended horizontally between the two poles of a strong horse shoe magnet in such a way that the axis of rod is horizontal and the direction of the magnetic field is vertically upward. The rod is connected in series with a battery and a key.

State giving reason:

1. What is observed when a current is passed through the aluminium rod from end B to end A?
2. What change is observed in a situation in which the axis of the rod 'AB' is moved and aligned parallel to the magnetic field and current is passed in the rod in the same direction?

When does a solenoid behave as a magnet? Draw the pattern of the magnetic field produced inside it showing the directions of the magnetic field lines.

Two LED bulbs of 12W and 6W are connected in series. If the current through 12W bulb is 0.06A the current through 6W bulb will be ______.