Current Electricity Test

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Current Electricity Test - 62

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Question 1
1 / -0

A potentiometer wire of length $$10 m$$ is connected in series with a battery. The e.m.f. of a cell balances against $$250 cm$$ length of wire. If length of potentiometer wire is increased by $$1 m$$, the new balancing length of wire will be

A
$$2.00 m$$

B
$$2.25 m$$

C
$$2.50 m$$

D
$$2.75 m$$

Solution

$$l=10m$$
Balancing length$$=250cm=2.5m$$
Lets, voltage drop across $$10m=V\quad Volt$$
$$\implies $$ Voltage drop across $$1m=\dfrac V{10}=0.v$$
$$\implies $$ Voltage drop across $$2.5m=0.25V$$
Now, we know the e.m.f of cell=$$0.25V$$
Case=$$II$$ When $$l=11m$$
Lets, voltage drop across $$11m=V\quad Volt$$
To drop V potential we use $$11m$$ long wire.
To drop $$1V$$ of potential we will find the balancing length at $$=\dfrac{}{V}m$$
To drop $$0.25V$$ balancing length will be $$=\dfrac11{V}\times 0.25V$$
$$=2.75m$$
Question 2
1 / -0

Figure below shows a portion of an electric circuit with the currents in amperes and their directions. The magnitude and direction of the current in the portion $$PQ$$ is

A
$$0 A$$

B
$$3 A$$ from $$P$$ to $$Q$$

C
$$4 A$$ from $$Q$$ to $$P$$

D
$$6 A$$ from $$Q$$ to $$P$$

Solution

At junction the net current arriving should be equal to the net current leaving
The net current $$8+2=4+2+1+x$$, $$x=3A$$
Now at junction Q the net current arriving is $$3+3=6A$$. This will flow toward P.
Question 3
1 / -0

The best instrument for accurate measurement of emf of a cell.

A
Potentiometer

B
Wheatstone Bridge

C
Voltmeter

D
Ammeter

Solution
Question 4
1 / -0

Two resistors $$400\ \Omega $$ and $$800\ \Omega$$ are connected in series with a 6 V battery. the potential difference measured by voltmeter across $$400\ \Omega $$ resistor is:

A
$$2\ V$$

B
$$1.95\ V$$

C
$$3.8\ V$$

D
$$4\ V$$

Solution

Total resistance of the circuit (series combination) $$R_s = R_1+R_2$$
$$\therefore$$ $$R_s = 400+800 =1200\Omega$$

Current, $$I=\dfrac{E}{R_s}=\dfrac{6}{1200}$$

$$I=0.005\ A$$

Potential difference across $$R_1$$, $$V' = IR_1$$
$$\therefore$$ $$V' = 0.005 \times 400$$
$$V' =2\ V$$
Question 5
1 / -0

A voltmeter having a resistance of $$998\Omega$$ is connected to a cell of emf $$2$$V and internal resistance $$2\Omega$$. The error in the measurement of emf will be.

A
$$4\times 10^{-1}$$V

B
$$2\times 10^{-3}$$V

C
$$4\times 10^{-3}$$V

D
$$2\times 10^{-1}$$V

Solution

$$I=\displaystyle \frac{2}{99}=\frac{2}{1000}=2\times 10^{-3}$$A
$$=2$$mA
Internal resistance is $$2\Omega$$
Hence, the measure of emf will be
$$E=2-I\times 2$$
$$=2-2mA\times 2$$
Therefore, error in measured value $$=4\times 10^{-3}$$V.
Question 6
1 / -0

A potentiometer is an ideal device of measuring potential difference because

A
It uses a sensitive galvanometer

B
It is an elaborate arrangement

C
It has a long wire hence heat developed is quickly radiated

D
It does not disturb the potential difference it measures

Solution

In balance condition, potentiometer does not take the current from secondary circuit.
Question 7
1 / -0

The ratio of resistance of two copper wire of the same length and of same cross-sectional area, when connected in series to that when connected in parallel, is

A
$$1 : 1$$

B
$$1 : 2$$

C
$$2 : 1$$

D
$$4 : 1$$

E
$$1 : 4$$

Solution

Let $$R$$ be the resistance of copper wire. In the first condition,
$$R_{series} = R + R = 2R .... (i)$$
In the second condition,
$$\dfrac {1}{R_{parallel}} = \dfrac {1}{R} + \dfrac {1}{R} = \dfrac {1}{R_{parallel}} = \dfrac {1 + 1}{R}$$
$$R_{parallel} =\dfrac {R}{2} ..... (ii)$$

On dividing Eq. (i) by Eq. (ii), we get

$$\dfrac {R_{series}}{R_{parallel}} = \dfrac {2R}{\dfrac {R}{2}} = \dfrac {4}{1}$$.
Question 8
1 / -0

Pick out the wrong feature about carbon resistors

A
Compact

B
Inexpensive

C
Relatively sensitive to temperature

D
Mostly used for higher resistor values

E
Colour codes express their resistor values

Solution

Carbon Resistor
The carbon resistor is a resistor which is made of carbon or graphite.
It is small in size and are light in weight.
It is suitable for high frequency circuits.
It has low temperature coefficient value.
Using this high value resistor can easily be made.
Question 9
1 / -0

Kirchhoff's first law ie, $$\displaystyle \Sigma i=0$$ at a junction is based on the law of conservation of

A
Charge

B
Energy

C
Momentum

D
Angular momentum

Solution

Kirchhoff's first law is based on the law of conservation of charge.
Question 10
1 / -0

The diagram shows identical lamps X and connected in series with a battery. The lamps light with normal brightness.If a third lamp Z is connected in parallel with lamp X, then what will happens to the brightness of the lamp Y?

A
Brighter than normal

B
Normal

C
Dimmer than normal

D
Very dim (cannot be seen)

Solution

The third lamp Z is connected parallel to X, so the current gets divided among X and Z. So both bulbs Xand Z light dimmer and the bulb Y lights brighter than earlier because current through it increases.

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Re-Attempt Weekly Quiz Competition

Current Electricity Test - 62

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Current Electricity Test - 62

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SHARING IS CARING

Question 1

$$2.00 m$$

$$2.25 m$$

$$2.50 m$$

$$2.75 m$$

Solution

Question 2

$$0 A$$

$$3 A$$ from $$P$$ to $$Q$$

$$4 A$$ from $$Q$$ to $$P$$

$$6 A$$ from $$Q$$ to $$P$$

Solution

Question 3

Potentiometer

Wheatstone Bridge

Voltmeter

Ammeter

Solution

Question 4

$$2\ V$$

$$1.95\ V$$

$$3.8\ V$$

$$4\ V$$

Solution

Question 5

$$4\times 10^{-1}$$V

$$2\times 10^{-3}$$V

$$4\times 10^{-3}$$V

$$2\times 10^{-1}$$V

Solution

Question 6

It uses a sensitive galvanometer

It is an elaborate arrangement

It has a long wire hence heat developed is quickly radiated

It does not disturb the potential difference it measures

Solution

Question 7

$$1 : 1$$

$$1 : 2$$

$$2 : 1$$

$$4 : 1$$

$$1 : 4$$

Solution

Question 8

Compact

Inexpensive

Relatively sensitive to temperature

Mostly used for higher resistor values

Colour codes express their resistor values

Solution

Carbon Resistor

The carbon resistor is a resistor which is made of carbon or graphite.It is small in size and are light in weight. It is suitable for high frequency circuits. It has low temperature coefficient value. Using this high value resistor can easily be made.

Question 9

Charge

Energy

Momentum

Angular momentum

Solution

Question 10

Brighter than normal

Normal

Dimmer than normal

Very dim (cannot be seen)

Solution

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The carbon resistor is a resistor which is made of carbon or graphite.
It is small in size and are light in weight.
It is suitable for high frequency circuits.
It has low temperature coefficient value.
Using this high value resistor can easily be made.