Advertisements
Advertisements
Question
Two resistors of equal resistances are joined in series and a current is passed through the combination. Neglect any variation in resistance as the temperature changes. In a given time interval,
(a) equal amounts of thermal energy must be produced in the resistors
(b) unequal amounts of thermal energy may be produced
(c) the temperature must rise equally in the resistors
(d) the temperature may rise equally in the resistors
Solution
(a) equal amounts of thermal energy must be produced in the resistors
(d) the temperature may rise equally in the resistors
In a resistor of resistance R, current i is passed for time t then the thermal energy produced in the resistor will be given by
H = i2Rt.
As the resistors are in series, the current through them will be same. Thus, the amount of thermal energy produced in the resistors is same. The rise in the temperature of the resistance will depend on the shape and size of the resistor. Thus, the rise in the temperature of the two resistances may be equal.
APPEARS IN
RELATED QUESTIONS
Three resistors 1 Ω, 2 Ω, and 3 Ω are combined in series. What is the total resistance of the combination?
Two electric bulbs P and Q have their resistances in the ratio of 1 : 2. They are connected in series across a battery. Find the ratio of the power dissipation in these bulbs
Two heating elements of resistances R1 and R2 when operated at a constant supply of voltage, V, consume powers P1 and P2 respectively. Deduce the expressions for the power of their combination whey they are, in turn, connected in (i) series and (ii) parallel across the same voltage supply.
Two resistances R and 2R are connected in parallel in an electric circuit. The thermal energy developed in R and 2R are in the ratio _______________ .
Suppose you have three resistors of 20 Ω, 50 Ω and 100 Ω. What minimum and maximum resistance can you obtain from these resistors?
Each of the resistors shown in the figure has a resistance of 10 Ω and each of the batteries has an emf of 10 V. Find the currents flowing through the resistors a and bin the two circuits.
Find the current measured by the ammeter in the circuit shown in the figure.
The voltmeter shown in the figure reads 18 V across the 50 Ω resistor. Find the resistance of the voltmeter.
An ammeter together with an unknown resistance in series is connected across two identical batteries each of emf 1.5 V. When the batteries are connected in series, the galvanometer records a current of 1A and when the batteries are in parallel, the current is 0.6A. Then the internal resistance of the battery is ______.
In parallel combination of n cells, we obtain ______.
If two resistors of resistances R1 = (4 ± 0.5) Ω and R2 = (16 ± 0.5) Ω are connected in series. The eqivalent resistance with the limits of percentage error is ______.
How many times will the resistance of an identical conductor be increase, if the parallel resistance be change to series one?
A condenses having a capacity 2.0 µF is charged to 200 V and the plates of the capacitor are connected to a resistance wire. The heat produce in it will be:-
Two electric lamps of each 40 watt are connected in series. The power consumed by the combination will be
An electric cable of copper has just one wire of radius 9 mm. Its resistance is 14Ω. If this single copper wire of the cable is replaced by seven identical well insulated copper wires each of radius 3 mm connected in parallel, then the new resistance of the combination will be:
Eight identical cells, each of emf 2V and internal resistance 3 Ω, are connected in series to form a row. Six such rows are connected in parallel to form a battery. This battery is now connected to an external resistor R of resistance 6 Ω. Calculate:
- emf of the battery.
- internal resistance of the battery.
- current flowing through R.
