Watt Hour Meter

Q.

Kilowatt is the unit of electrical _____ but kilowatt-hour is the unit of electrical _____.

Q.

What is meant by electric flux? Write its SI unit.

Q.

An electric heater is rated 1500 W. How much energy does it use in 10 hours?

Q. Difference between kilowatt and kilowatt hour

Q.

The unit in which the domestic electric meters measure the electrical energy consumed and its value in SI unit is:

1. Kilowatt-hour (kWh) and 1 kWh = 3.6 X 10⁶J

2. Watt-hour (Wh) and 1 Wh = 3.6 X 10³J

3. Joule and 1KJ = 1000J

4. Joule and 1 J =1000kJ

Q.

The main fuse is connected in :

(a) live wire

(b) neutral wire

(c) both the live and earth wires

(d) both the earth and neutral wires.

Q.

State the function of each of the following in a house circuiting :

(a) kWh meter, (b) main fuse, and (c) main switch.

Q.

Where is the main fuse connected in a house circuit?

Q.

The energy of a thermal neutron is about ______

1. 0.025 ev

2. 0.25 ev

3. 0.0025 ev

4. 0.00025 ev

Q. In a house, $3$ fans of $200$ watt each are used for $12$ hours per day, a TV of $500$ watt is used for $10$ hours per day, $4$ bulbs of $60$ watt each are used for $8$ hours per day. Find the electric bill for the month of $30$ days if the cost of one unit is Rs. $2.20$.

Q.

Why don't we use Joule as commercial unit? How many Joule will make up 1kWh.

Q.

The output energy is always greater than the input energy.

1. True
2. False

Q. Define watt-hour.How many joules are equal to 1 watt-hour?

Q.

The electrical energy used in our houses is measured in__________.

Q.

One unit of electrical energy is equal to

1. $3.6J$

2. $1.6\times {10}^{6}J$

3. $1kWh$

4. $1\frac{kW}{s}$

Q.

A fan of 60 W runs for 75 hours in a month. How much energy is consumed?

Q.

Which uses more energy, a 250 W TV set in 1 h, or a 1200 W toaster in 10 minutes?

Q.

When a 0.5 kW heater operates for 20 minutes, what is the electrical energy consumed (in kJ)?

Q. Which of the statements are true about ring system?

1. Each appliance has seperate fuse.
2. Connections of all appliances with the mains are in series.
3. The plugs and socket are of same size.
4. Current can travel to individual appliances through two seperate paths.

Q.

A metal drill of power 40 W, drills a hole in a lead cube of mass 1 kg in 8.5 seconds. The specific heat capacity of lead is 130 Jkg^–1°C^–1. If all the mechanical energy of the drill changes into heat energy, calculate the rise in temperature of lead cube.

1. 0.62°C = θ

2. 0.38°C = θ

3. 2.62°F = θ

4. 2.62°C = θ

Q.

In a house 5 CF lamps each of 24 W works for a period of 5 hours and 2 fans of 80 W for 5 hours. What is the electric consumption in kWh for a month?

1. 42 kWh

2. 24 kWh

3. 60 kWh

4. 18 kWh

Q. What is the cost of using the iron for the month of January 10 has a day is 1 kilowatt hour cost rupees 3.40

Q.

In what unit does the electric meter in a house measure the electrical energy consumed? What is its value in S.I unit?

Q. $\text{Assertion (A)}:$ The neutral wire is used to direct any leaking charges into the Earth.

$\text{Reason (R)}:$ Fuses are always connected in series with the live wire.

Which of the following is correct?

1. Both $\text{A}$ and $\text{R}$ are true and $\text{R}$ is the correct explanation of $\text{A}$.
2. Both $\text{A}$ and $\text{R}$ are true and $\text{R}$ is not the correct explanation of $\text{A}$.
3. $\text{A}$ is true, but $\text{R}$ is false.
4. $\text{A}$ is false, but $\text{R}$ is true.

Q.

One watt-hour is equal to:

1. $36J$

2. $360J$

3. $3600J$

4. $36,000J$

Q.

A battery of 9 V is connected in series with resistors of 0.2W, 0.3W, 0.4W, 0.5W and 12W. How much current would flow through the 12W resistor? (Give the answer in A to 2 decimal places)

1. 0.67

2. 0.90

3. 0.76

4. 0.87

Q. In a house there are six $100W$ bulb, which are used for $6hours$ per day. Calculate the energy consumed in $kWh$ in a day.

1. $3600kWh$
2. $3.6kWh$
3. $360kWh$
4. $36kWh$

Q.

$kWh$ is the unit of ___________.

Q.

An electric bulb is rated $220V$ and $100W.$ When it is operated at $110V,$ the power consumed will be

1. $100\text{W}$
2. $75\text{W}$
3. $50\text{W}$
4. $25\text{W}$

Q.

Kilowatt-hour is equal to _____

1. 360000 J

2. 3600 J

3. 3600000 J

4. 360 J