Heating Effect of Current

Q. An electric kettle consumes 1 KW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

1. 1 A
2. 2 A
3. 4 A
4. 5 A

Q.

State and explain Joules Law of Heating?

Q.

An electric bulb is connected to a $220V$ generator the current is $0.50A$ What is the power of the bulb?

Q.

An electric bulb is connected to a 220V generator , the current is 0.50A . calculate the power of the bulb

Q.

Two lamps, one rated 40 W at 220 V and the other 60 W at 220 V, are connected in parallel to the electric supply at 220 V.

(a) Craw a circuit diagram to show the connections.

(b) Calculate the current drawn from the electric supply.

(c) Calculate the total energy consumed by the two lamps together when they operate for one hour.

Q.

Q1) An electric iron consumes energy at a rate of 840W ehen heating is in at maximum and 360W when heating is at minimum. The voltage is 220V. What are current and resistance in each case?

Q2) Which uses more energy, a250W set in 1hour OR a 1200W toaster in 10 minutes?

Q3) What is the role of split rings in DC motor?

Q4) Write the principal of generator?

Q5) Write the function of brush in generator?

Q.

Which of the following terms does not represent electrical power in a circuit?

1. ${\mathrm{I}}^2\mathrm{R}$

2. ${\mathrm{IR}}^2$

3. $\mathrm{VI}$

4. $\frac{{\mathrm{V}}^2}{\mathrm{R}}$

Q.

Name the factors on which the heat produced in a wire depends when current is passed in it and state how does it depend on the factors stated by you.

Q.

Compare the power used in 2 ohm resistor in each of the following circuits

a)6 volt battery in series with 1 ohm and 2 ohm resistors

And

b)4 volt battery in parallel with 12 ohm and 2 ohm resistors

Q.

What Is The Difference Between Electric Energy And Electric Power?

Q.

Explain the physical properties of metals with suitable examples

Q.

(a) Derive the expression for the heat produced due to a current I flowing for a time interval t through a resistor R having a potential difference V across its ends. With which name is this relation known?
(b) How much heat will an instrument of 12 W produce in one minute if it is connected to a battery of 12 V?
(c) The current passing through a room heater has been halved. What will happen to the heat produced by it?
(d) What is meant by the heating effect of current? Give two applications of the heating effect of current.
(e) Name the material which is used for making the filaments of an electric bulb.

Q.

An electric kettle rated at 220 V, 2.2 kW, works for 3 hours. Find the energy consumed and the current

Q.

The transformer with efficiency 80%works at 4kw and 100V. If the secondary voltage is 200 V then the primary and secondary currents are respectively?

Q.

The correct relation between heat produced (H) and electric current (I) flowing is

1. H directly proportional to (1/I)

2. H directly proportional to I

3. H directly proportional to (1/I²).

4. H directly proportional to I²

Q.

An electric oven of 2 kW power rating is operated in a domestic electric circuit that has a current rating of 5A. If the supply voltage is 220V, what result do you expect? Explain.

Q.

Why is Copper most used for electrical wiring?

Q.

Derive the formula P = VI of electric power.

Q.

Name two devices which work on the heating effect of electric current.

Q.

What is nichrome ? State its one use.

Q.

Electric fuses are always connected in series with the live wire.

1. True

2. False

Q.

Give two reasons why nichrome alloy is used for making the heating elements of electrical applicances.

Q.

Name two effects produced by electric current.

Q.

In the following circuits (Figure 12.2), heat produced in the resistor or combination of resistors connected to a 12 V battery will be:

1. maximum in case (iii)

2. maximum in case (ii)

3. minimum in case (i)

4. same in all cases

Q.

When the current in a conductor is doubled keeping other parameters constant, the heat energy produced will be _____ the initial value:

1. becomes 3 times

2. is unaffected

3. is doubled

4. becomes 4 times

Q.

Name the material used for (i) filament of an electric bulb, , and (ii) heating element of a room heater.

Q.

Write a short note on fuse

Q.

Why does an LC circuit not consume any power?

Q. The electric power of a device can be calculated using P=I²R or P=V²/R .
The first expression indicates that the resistance is directly proportional.where as in the second one the R is inversely proportional. How can the seemingly different dependence between P and R in these expressions be explained .

Q.

The heat produced by passing an electric current through a fixed resistor is proportional to the square of :
(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed