(English Medium) ICSE Class 10 - CISCE Question Bank Solutions

Complete the following table. The first answer has been given as an example

The following appliances are to be used on 240 V supply. Calculate the current used by each and say which fuse, 2 amp, 5 amp or 13 amp should be incorporated with each, (i) A television rated at 150 W, (ii) An electric iron rated at 750 W, (iii) An immersion heater rated at 3000 W, (iv) A hair dryer rated at 500 W. How much will it cost to run the television set for 100 days for an average of 4 hours a day at 60 paise per unit?

What is the purpose of fuse in an electrical circuit?

What is the criteria for selecting a fuse wire?

If a fuse contains a 5 A fuse wire and the voltage is 240 V, what is the maximum power (wattage) which may be taken from the circuit?

What would be the danger involved in replacing a blown fuse with the one which would carry a large current?

An electric kettle has a heating element which is rated at 2 kW when connected to a 250 V electric supply. Calculate the
(a) Current which flows in the element when it is connected to a 250 V supply,
(b) Resistance of the filament,
(c) Heat produced in 1 minute by the element,
(d) Cost of running the kettle for 10 minutes a day for 30 days of the month, at the rate of Rs. 3.00 per unit.

60 joules of heat was dissipated in a resistor when 20 C flowed for 5 s. Calculate:
(a) P.d. across the resistor,
(b) Resistance of the resistor, and
(c) Average power dissipated in the resistor.

Fig.  shows a 3 pin plug with the cover removed. The electric cable
connected to the plug contains 3 wires with colour coded insulation namely brown, blue and green.

1. Identify each of the colour coded wires by stating to which of the
   terminals A, B or C in the diagram they should be connected.
2. Identify the terminal through which no current passes in normal
   circumstances.
3. What is the purpose of the earthed wire connected to an electric
   appliance like an electric heater? Describe how it works.

An electric oven is rated as 1.5 kW, 250 V. If it is connected to a 250 V mains, calculate the
(a) Current drawn,
(b) Energy consumed in 20 hours,
(c) Cost of energy consumed in 20 hours at the rate of Re. 1 per unit.

An auto lamp is joined to a battery of e.m.f. 4 V and internal resistance 2.5Ω. A steady current of 0.5 A flows through the circuit. Calculate the
(a) Total energy provided by battery in 10 minutes,
(b) Heat dissipated in the bulb in 10 minutes.

Explain with the help of a diagram how does 'short circuiting' occur in an electric kettle.

Electrical appliances have voltage and power ratings as listed below. Which
has the larger working resistance?

If the potential differences between two parts of a thundercloud is 10s V,
what is the amount of energy given up during the passage of 20 coulombs?

(a)2x10-7J

(b)200J

(c)Sx106 j

(d)2x 109J

(e)2x 1010 J

A 3 pin mains plug is fitted to the lead for a 1 kW electric kettle to be used on a 250 V A.C. supply. Which of the following statements is NOT correct?
(a) A 13 A fuse is the most appropriate value to use.
(b) The brown wire should be connected to the live side of the mains.

Name the principle on which a transformer works.

What is the function of a step-up transformer?