33. How will you conclude that the same potential difference (voltage) exists across three resistors connected in a parallel arrangement to a battery?
Answer: Take three resistors R1, R2 and R3, a battery, an ammeter, a voltmeter and some wires. Complete the circuit; as shown in the diagram.
34. What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.
Answer: The Joule’s Law of Heating states that the heat produced in a resistor is:
This can be expressed by following equation:`H=I^2` Rt
Where, I is electric current, R is resistance, t is time and H is the heating effect of electric current.
This can be demonstrated by a simple experiment, in which an immersion rod water heater can be used. This should be connected to a regulator which we use for regulating the speed of an electric fan.
35. Find out the following in the electric circuit given in following figure.
(a) Effective resistance of two 8 Ω resistors in the combination
Answer: Let the total effective resistance in the combination = R
Therefore,`1/R= 1/(8Ω)+1/(8Ω)= (1+1)/(8 Ω)``=2/(8 Ω)=1/(4 Ω)`
Therefore, effective resistance = 4Ω
(b) Current flowing through 4 Ω resistor
Answer: Given, potential difference through the circuit, V = 8V
The total effective resistance of the circuit, R = resistance in series + effective resistance in parallel combination
⇒R = 4Ω + 4Ω = 8Ω
Thus,electric current,I through the circuit`= V/R`
Since, there is no division of electric current in series combination,
thus, electric current through the 4Ω resistor = 1A
(c) Potential difference across 4 Ω resistance
Answer: Since there is no division of electric current, in the case of series connection.
Thus, electric current through the 4Ω resistor = 1A
Since,potential difference,V across the 4Ω resistor=IR
(d) Power dissipated in 4 Ω resistor
Answer: Electric current, I = 1A
Potential difference, through 4Ω resistor = 4V
Thus, power, P = V x I
⇒P = 4V x 1A = 4 watt
Thus, power dissipated in 4Ω resistor = 4W
(e) Difference in ammeter readings, if any.
Answer: Since resistors are connected in series, thus there is no difference in ammeter readings.
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