Observe the circuit diagram given below and answer the following questions.
a. Which are the instruments labeled as P and Q in the diagram?
b. If you replace the copper wire AB with a Nichrome wire of same length and area of cross-section.
i. What change would you notice in the reading on the device Q? Why?
ii. What will happen to the heat produced in the conductor? Explain with reference to Joule's Law.

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Solution

a. P- Rheostat
Q- Ammeter
b. i. Reading will decrease. Due to higher resistance current decreases.
ii. Because of Nichrome's high resistivity, the current in the circuit will decrease.
According to Joules law $H = I^{2} R t$ , decrease in the amount of current will reduce the amount of heat.

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a. P- Rheostat Q- Ammeterb. i. Reading will decrease. Due to higher resistance current decreases. ii. Because of Nichrome's high resistivity, the current in the circuit will decrease. According to Joules law H=I2Rt, decrease in the amount of current will reduce the amount of heat.

a. P- Rheostat
Q- Ammeter
b. i. Reading will decrease. Due to higher resistance current decreases.
ii. Because of Nichrome's high resistivity, the current in the circuit will decrease.
According to Joules law $H = I^{2} R t$ , decrease in the amount of current will reduce the amount of heat.