English Medium इयत्ता १० - CBSE Question Bank Solutions for Science

 An electrician has wired a house in such a way that if a lamp gets fused in one room of the house, all the lamps in other rooms of the house stop working. What is the defect in the wiring?

Draw a circuit diagram showing two electric lamps connected in parallel together with a cell and a switch that works both lamps. Mark an â’¶ on your diagram to show where an ammeter should be placed to measure the current.

The lamps in a house hold circuit are connected in parallel because:

(a) this way they required less current
(b) if one lamp fails the others remain lit
(c) this way they require less power
(d) if one lamp fails the other also fail

Using the circuit given below, state which of the following statement is correct?  

(a) When S₁ and S₂ are closed, lamps A and B are lit.₂2
(b) With S₁ open and S₂ closed, A is lit and B is not lit.
(c) With S₂ open and S₁ closed A and B are lit.
(d) With S₁ closed and S₂ open, lamp A remains lit even if lamp B gets fused.

 Draw a circuit diagram showing two lamps, one cell and a switch connected in series.
 How can you change the brightness of the lamp?

Consider the circuit given below when A, B and C are three identical light bulbs of constant resistance.   

(a) List the bulbs in order of increasing brightness.
(b) If C burns out, what will be the brightness of A now compared with before?
(c) If B burns out instead, what will be the brightness of A and C compared with before?

How do you think the brightness of two lamps arranged in parallel compares with the brightness of two lamps arranged in series (both arrangements having one cell)?

In which of the following cases more electrical energy is consumed per hour?

(i) A current of 1 ampere passed through a resistance of 300 ohms.
(ii) A current of 2 amperes passed through a resistance of 100 ohms. 

For a heater rated at 4 kW and 220 V, calculate:

(a) the current,
(b) the resistance of the heater,
(c) the energy consumed in 2 hours, and
(d) the cost if 1 kWh is priced at Rs 4.60.

Two lamps, one rated 40 W at 220 V and the other 60 W at 220 V, are connected in parallel to the electric supply at 220 V.  

(a) Draw a circuit diagram to show the connections.
(b) Calculate the current drawn from the electric supply.
(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.

An electric bulb is rated as 10 W, 220 V. How many of these bulbs can be connected in parallel across the two wires of 220 V supply line if the maximum current which can be drawn is 5 A? 

How does the heat H produced by a current passing through a fixed resistance wire depend on magnitude of current I?

If the current passing through a conductor is doubled, what will be the change in heat produced

Which effect of current is utilised in an electric light bulb?

Which effect of current is utilised in the working of an electric fuse?

Name two devices which work on the heating effect of electric current.

State three factors on which the heat produced by an electric current depends. How does it depend on these factors? 

Which effect of current can be utilised in detecting a current carrying wire concealed in a wall? 

Name the scientist who discovered the magnetic effect of current.