# Thermal and Chemical Effects of Electric Current HC Verma Solutions of Que for Short Ans Ch-33 Vol-2

Thermal and Chemical Effects of Electric Current HC Verma Solutions of Que for Short Ans Ch-33 Vol-2 Concept of Physics. Step by Step Solution of Questions for short answer of Ch-33 Thermal and Chemical Effects of Electric Current HC Verma Question of Bharti Bhawan Publishers . Visit official Website CISCE for detail information about ISC Board Class-12 Physics.

## Thermal and Chemical Effects of Electric Current HC Verma Solutions of Que for Short Ans Ch-33 Vol-2

 Board ISC and other board Publications Bharti Bhawan Publishers Ch-33 Thermal and Chemical Effects of Electric Current Class 12 Vol 2nd writer H C Verma Book Name Concept of Physics Topics Solutions of Question for Short Answer Page-Number 217

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Thermal and Chemical Effects of Electric Current H C Verma Que for Short Ans

### Solutions of Ch-33 Vol-2 Concept of Physics for Class-12

(Page – 217)

#### Question 1 :-

If a constant potential difference is applied across a bulb, the current slightly decreases as time passes and then becomes constant. Explain.

Answer 1 :-

As a constant potential difference is applied across a bulb, due to Joule’s heating effect, the temperature of the bulb increases. As the temperature of the bulb filament increases, its resistance also increases, as resistance R is the function of temperature T. It is given by R = R0(1+αT). With an increase in the value of resistance, the value of current decreases as i=(V/R). Now, the heat generated by the resistance is constantly radiated to the surroundings. Thus, the value of its temperature is maintained and hence its resistance. As a result, current through the bulb filament becomes constant.

#### Question 2 :-

Two unequal resistances, R1 and R2, are connected across two identical batteries of emf ε and internal resistance r (see the figure). Can the thermal energies developed in R1 and R2 be equal in a given time? If yes, what will be the condition?

Answer 2 :-

For the given time t, let the currents passing through the resistance R1 and R2 be i1 and i2, respectively.

Applying Kirchhoff’s Voltage Law to circuit-1, we get:-

Similarly, the current in the other circuit,

The thermal energies through the resistances are given by

#### Question 3 :-

When a current passes through a resistor, its temperature increases. Is it an adiabatic process?

Answer 3 :-

No, the rise in the temperature of a resistor on passing  current through it is not an adiabatic process. In an adiabatic process, there is no heat exchange between the system and the surroundings.

#### Question 4 :-

Apply the first law of thermodynamics to a resistor carrying a current i. Identify which of the quantities ∆Q, ∆U and ∆W are zero, positive and negative.

Answer 4 :-

The battery is doing positive work on a resistor carrying current i. Thus, ∆W is positive. The work done on the resistor is used to increase its thermal energy; thus ∆Q is positive. As the temperature of the resistor rises, ∆U is positive.

Is inversion temperature always double the neutral temperature? Does the unit of temperature have an effect in deciding this question?

Answer 6 :-

If the inversion temperature and neutral temperature are measured in degree Celsius, then it is correct to say that “inversion temperature is always double the neutral temperature.” When temperature is measured in other units, such as Kelvin, then inversion temperature is not the double of neutral temperature.

No, the neutral temperature is not always the arithmetic mean of the inversion temperature and the temperature of the cold junction. That is valid only when the unit of temperature is degree Celsius.

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