English Medium इयत्ता १० - CBSE Question Bank Solutions for Science

The heat produced by passing an electric current through a fixed resistor is proportional to the square of:  

(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed

The current passing through an electric kettle has been doubled. The heat produced will become:

(a) half
(b) double
(c) four time
(d) one-fourth 

An electric fuse works on the:
(a) chemical effect of current
(b) magnetic effect of current
(c) lighting effect of current
(d) heating effect of current

The elements of electrical heating devices are usually made of:

(a) tungsten
(b) bronze
(c) nichrome
(d) argon

The heat produced in a wire of resistance 'x' when a current 'y' flows through it in time 'z' is given by:

(a) x² × y × z
(b) x × z × y²
(c) y × z² × x
(d) y × z × x 

Which of the following characteristic is not suitable for a fuse wire?

(a) thin and short
(b) thick and short
(c) low melting point
(d) higher resistance than rest of wiring

If the current flowing through a fixed resistor is halved, the heat produced in it will become:

The electrical resistivities of four materials P, Q, R and S are given below:

How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows?

What property of the filament wire accounts for this difference?

Two exactly similar heating resistances are connected (i) in series, and (ii) in parallel, in two different circuits, one by one. If the same current is passed through both the combinations, is more heat obtained per minute when they are connected in series or when they are connected in parallel? Give reason for your answer.

An electric iron is connected to the mains power supply of 220 V. When the electric iron is adjusted at 'minimum heating' it consumes a power of 360 W but at 'maximum heating' it takes a power of 840 W. Calculate the current and resistance in each case. 

Which electric heating device in your home do you think have resistors which control the flow of electricity?

Name the phenomenon responsible for the following effect:
When we sit in front of a plane mirror and write with our right hand, if appears in the mirror that we are writing with the left hand.

If an object is placed at a distance of 10 cm in from of a plane mirror, how far would it be from its image?

Which property of light makes a pencil cast a shadow when it is held in front of a light source?

Fill in the following blank with a suitable word:
When light is reflected, the angles of incidence and reflection are ............ .

State whether the following statement is true of false:
A student says that we can see an object because light from our eyes is reflected back by the object.

Where is the image when you look at something in a mirror?

A ray of light strikes a plane mirror such that its angle of incidence is 30°. What angle does the reflected ray make with the mirror surface?

The letter F is placed in front of a plane mirror: 

 How would its image look like when seen in a plane mirror?