1. Question: Two bulbs have ratings 100 W, 220 V and 60 W, 220 V respectively. Which one has a greater resistance?
2. Question: A torch bulb has a resistance of 1 Ω when cold. It draws a current of 0.2 A from a source of 2 V and glows. Calculate
(i) the resistance of the bulb when glowing and
(ii) explain the reason for the difference in resistance.
3. Question: Calculate the resistance of 1 km long copper wire of radius 1 mm. (Resistivity of copper = 1.72 x 1 0-8
4. Question: When a potential difference of 2 V is applied across the ends of a wire of 5 m length, a current of 1 A is found to flow through it. Calculate:
(i) the resistance per unit length of the wire
(ii) the resistance of 2 m length of this wire
(iii) the resistance across the ends of the wire if it is doubled on itself.
5.Question: How much work is done in moving 4 C across two point having pd. 10 v
6. Question: How much energy is given to each coulomb of charge passing through a 9 v battery?
7. Question: 100 j of work is done in moving a charge of 5 C from one terminal of battery to another . What is the potential difference of battery?
8. Question: If 4 x 10 -3 J of work is done in moving a particles carrying a charge of 16 x 10 - 6 C from infinity to point P .What will be the potential at a point?
9. Question: Calculate the current and resistance of a 100 W ,200V electric bulb.
10. Question: Calculate the power rating of the heater coil when used on 220V supply taking 5 Amps.
11. Question: A lamp can work on a 50 volt mains taking 2 amps.What value of the resistance must be connected in series with it so that it can be operated from 200 volt mains giving the same power.
12. Question: Calculate the work done in moving a charge of 5 coulombs from a point at a potential of 210 volts to another point at 240 volts
13. Question: How many electrons pass through a lamp in one minute if the current be 220 mA?
14. Question: Calculate the current supplied by a cell if the amount of charge passing through the cell in 4 seconds is 12 C ?
15. Question: A 2 Volt cell is connected to a 1 Ω resistor. How many electrons come out of the negative terminal of the cell in 2 minutes?