Question

EXERCISES
1.
(d) 25
3.
6.
be A piece of wire of resistance R is cut into five equal parts. These arts are then
connected in parallel. If the equivalent resistance of this combination is r', then the
ratio R/R'is
(a) 1/25
(b) 1/5
(c) 5
2. Which of the following terms does not represent electrical power in a circuit?
(a) IR
(b) IR
(c) VI
(d) V/R
An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the
power consumed will be
(a) 100 W
(b) 75 W
(c) 50 W
(d) 25 W
4. Two conducting wires of the same material and of equal lengths and equal diameters
are first connected in series and then parallel in a circuit across the same potential
difference. The ratio of heat produced in series and parallel combinations would be
(a) 1:2
(b) 2:1
(c) 1:4
(d) 4:1
5. How is a voltmeter connected in the circuit to measure the potential difference between
two points?
A copper wire has diameter 0.5 mm and resistivity of 1.6 x 10-8 Q2 m. What will be
the length of this wire to make its resistance 102? How much does the resistance
change if the diameter is doubled?
7. The values of current I flowing in a given resistor for the corresponding values of
potential difference V across the resistor are given below -
I (amperes) 0.5 1.0 2.0 3.0 4.0
V (volts) 1.6 3.4 6.7 10.2 13.2
Plot a graph between V and I and calculate the resistance of that resistor.
8. When a 12 V battery is connected across an unknown resistor, there is a current
of 2.5 mA in the circuit. Find the value of the resistance of the resistor.
9. A battery of 9 V is connected in series with resistors of 0.2 , 0.3 22. 0.4 2.0.5
and 12 12, respectively. How much current would flow through the 12 22 resistor?
10. How many 176 12 resistors (in parallel) are required to carry 5 A on a 220 V line?
11. Show how you would connect three resistors, each of resistance 6 92, so that the
combination has a resistance of (1) 9 82. (ii) 4 22.
12. Several electric bulbs designed to be used on a 220 V electric supply line, are
rated 10 W. How many lamps can be connected in parallel with each other across
the two wires of 220 V line if the maximum allowable current is 5 A?
13. A hot plate of an electric oven connected to a 220 V line has two resistance coils
A and B, each of 24 12 resistance, which may be used separately, in series, or in
parallel. What are the currents in the three cases?
14. Compare the power used in the 2 Q2 resistor in each of the following circuits:
(i) a 6 V battery in series with 1 and 2 2 resistors, and (ii) a 4 V battery in parallel
with 12 12 and 2 12 resistors.
city

Answer 1

Answer:

2 C

3 100W

4 4:1

Explanation: