Electricity Test

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Electricity Test - 36

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Weekly Quiz Competition

Question 1
1 / -0

Fuse wire is made of :

A
Platinum

B
Copper

C
Aluminium

D
Alloy in tin and lead

Solution

Electric fuse wire is a wire which allows only upto a limit of current through it, if a particular amount of value of current is exceeded then it melts down.
so for achieving the melting property the fuse wire is made up of an alloy made of tin $$63 \ \%$$ & lead $$37\ \%$$. which can melt down over low temperatures.
Question 2
1 / -0

Two wires of same metal have the same length but their cross-sections area in the ratio 3 : 1. They are joined in series. The resistance of the thicker wire is $$10\Omega$$ .The total resistance of the combination will be:

A
$$40 \Omega$$

B
$$40/3 \Omega$$

C
$$5/2 \Omega$$

D
$$100 \Omega$$

Solution

(Let R' denote thicker and R denote thinner resistor)
We know,
$$ R = \dfrac{\rho \times L}{A} \implies \dfrac{R'}{R} = \dfrac{A}{A'} $$
$$ \implies \dfrac{10}{R} = \dfrac{1}{3} \implies R = 30 \Omega $$

Since they are connected in series,the equivalent resistance is given by,
$$ R^{}_{eq} = R + R' \implies R^{}_{eq} = 30 + 10 = 40 \Omega $$
Question 3
1 / -0

$$1kWh= $$ _________?

A
$$3600000\ J$$

B
$$10000\ J$$

C
$$4.2\ J$$

D
$$25000\ J$$

Solution

Kilowatt hour is the unit of energy to measure the amount of electricity used in an hour $$1\ kW$$ in $$1\ hr$$.
Hence,
$$1\ kWh = 1 kW \times 1\ hr$$
$$= 10^3 W \times 3600\ s$$
$$= 3600000\ J$$
Question 4
1 / -0

If $$R_{1}$$ and $$R_{2}$$ are the resistances of two resistors connected in series combination, their effective or net resistance is given by....

A
$$\frac{R_1R_2}{R_1+R_2}$$

B
$$R_1+R_2$$

C
$$R_1-R_2$$

D
$$R_1R_2$$

Solution

In a series combination of resistors, the end point of one resistor is connected to the starting point of second resistor. Then the effective resistance of the combination is equal to the sum of the resistances of individual resistors, If R1 and R2 are the resistances of two resistors connected in series combination, their effective or net resistance is given by $$R_{net}$$ = R1+R2. This is true for n' number of resistors connected in series combination.
Question 5
1 / -0

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

A
Power, Energy

B
Power, Electric potential

C
Power, Current

D
Energy, Power

Solution

In SI system, unit of power is Watt (W). Kilowatt is equal to one thousand ($$10^3$$) watts. The kilowatt-hour is a unit of energy and is equal to 1,000 watt-hours. If the energy is being transmitted or used at a constant rate (power) over a period of time, the total energy in kilowatt-hours is the product of the power in kilowatts and the time in hours.
Question 6
1 / -0

What is the maximum resistance one can make with ten $$1 \Omega$$ resistors?

A
$$1 \Omega$$

B
$$2 \Omega$$

C
$$5 \Omega$$

D
$$10 \Omega$$

Solution

Given ten $$1 \Omega$$ resistors.
If all these resistors are connected in series a maximum value of resistance is obtained then
$$R_{eq} = (1+1+1+1+1+1+1+1+1+1) \Omega = 10 \Omega$$
Question 7
1 / -0

Two fuse wires of the same length are rated 5 A and 20 A.Which of the fuse wires is thicker and why ?

A
5 A

B
20 A

C
Both have same thickness

D
Cannot be same

Solution

The resistance of a given length of flat fuse wire is inversely proportional to it`s thickness. Therefore increasing the thickness of a given fuse wire lowers the fuse resistance and thereby increases the amount of current the fuse can carry without generating enough heat to burn the fuse open.
Hence,among two fuse wires of the same length rated 5 A and 20 A,a higher rated fuse (i.e., 20 A fuse) will be thicker.
Question 8
1 / -0

An electric kettle is rated as $$2.5\ kW, \ 250\ V$$. Find the cost of running the kettle for two hours at $$60\ \text{paisa}/\text{unit}$$.

A
$$Rs\ 6$$

B
$$Rs\ 3$$

C
$$Rs\ 9$$

D
$$Rs\ 1$$

Solution

$$Rate=0.60 Rs/kWh$$
$$Energy=Power \times time$$
Energy consumed, $$E =2.5 \times 2 = 5\ kWh $$
Cost, $$C = 5 \times 0.60 = Rs\ 3 $$
Question 9
1 / -0

An air conditioner is rated $$240\ V, 1.5\ kW$$. The air conditioner is switched on $$8\ hrs$$ each day. What is electrical energy consumed in $$30\ days$$?

A
$$2.88\ kWh$$

B
$$360\ kWh$$

C
$$120\ kWh$$

D
$$240\ kWh$$

Solution

Energy consumed is given by:
$$E= Pt$$
$$E$$: Energy consumed
$$P$$: Power
$$t$$: Time
$$\Rightarrow E = 1.5\ kW \times 30 \times 8\ hrs$$
$$\Rightarrow E= 360\ kWh $$
Question 10
1 / -0

Five resistors each of 1 ohm are connected in parallel. The resultant resistance of the combination is :

A
$$ 5 \Omega$$

B
$$ 1 \Omega$$

C
$$ 0.2 \Omega$$

D
$$ 2 \Omega$$

Solution

$$\displaystyle R_{eq} = \frac{R}{5}$$
Given $$R= 1 \Omega$$
$$R_{eq} =\frac{1}{5} = 0.2 \Omega$$

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Electricity Test - 36

Result

Electricity Test - 36

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SHARING IS CARING

Question 1

Platinum

Copper

Aluminium

Alloy in tin and lead

Solution

Question 2

$$40 \Omega$$

$$40/3 \Omega$$

$$5/2 \Omega$$

$$100 \Omega$$

Solution

Question 3

$$3600000\ J$$

$$10000\ J$$

$$4.2\ J$$

$$25000\ J$$

Solution

Question 4

$$\frac{R_1R_2}{R_1+R_2}$$

$$R_1+R_2$$

$$R_1-R_2$$

$$R_1R_2$$

Solution

Question 5

Power, Energy

Power, Electric potential

Power, Current

Energy, Power

Solution

Question 6

$$1 \Omega$$

$$2 \Omega$$

$$5 \Omega$$

$$10 \Omega$$

Solution

Question 7

5 A

20 A

Both have same thickness

Cannot be same

Solution

Question 8

$$Rs\ 6$$

$$Rs\ 3$$

$$Rs\ 9$$

$$Rs\ 1$$

Solution

Question 9

$$2.88\ kWh$$

$$360\ kWh$$

$$120\ kWh$$

$$240\ kWh$$

Solution

Question 10

$$ 5 \Omega$$

$$ 1 \Omega$$

$$ 0.2 \Omega$$

$$ 2 \Omega$$

Solution

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