Current Electricity Test

Result

Current Electricity Test - 67

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Weekly Quiz Competition

Question 1
1 / -0

For comparing the electromotive force of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wire. Which of the following possibilities would make the experiment unsuccessful?

A
The electromotive force system of the standard cell is larger than the $$E$$ electromotive force system of the two cells.

B
The diameter of the wires is the same and uniform throughout

C
The number of wires is ten

D
The electromotive force of the standard cell is smaller than the electromotive force of the two cells.

Solution

The emf of the cell standard cell must be greater than that of experiment cells, otherwise balance point is not obtained.
Question 2
1 / -0

A circular coil of area $$8{m^2}$$ and number of turns 20 is placed in a magnetic field of 2T with its plane perpendicular to it. It is rotated with an angular velocity of 20rev/s about its natural axis. The emf induced is

A
$$400 V$$

B
$$800\pi V$$

C
$$Zero$$

D
$$400\pi V$$

Solution
Question 3
1 / -0

Three resistances $$R_1,R_2$$ & $$R_3$$ $$(R_1> R_2> R_3)$$ are connected in series. If current $$I_1,I_2$$ & $$I_3$$ respectively is flowing through them, the correct relation will be

A
$$I_1=I_2=I_3$$

B
$$I_1> I_2> I_3$$

C
$$I_1< I_2< I_3$$

D
$$I_1> I_2< I_3$$

Solution

In series, same amount of current will flow through all the resistances.
Current $$I_1=I_2=I_3=I=\dfrac{V}{R_{eq}}=\dfrac{V}{R_1+R_2+R_3}$$

Option A is correct.
Question 4
1 / -0

Eight resistances each of resistance $$5\Omega $$ are connected in the circuit as shown in figure. The equivalent resistance between $$A$$ and $$B$$ is

A
$$\dfrac{8}{3}\Omega $$

B
$$\dfrac{16}{3}\Omega $$

C
$$\dfrac{15}{7}\Omega $$

D
$$\dfrac{19}{2}\Omega $$

Solution
Question 5
1 / -0

Two resistances of $$400\Omega$$ and $$800\Omega$$ are connected in series with a $$6$$ volt battery of negligible internal resistance. A voltmeter of resistance $$10,000\Omega$$ is used to measure the potential difference across $$400\Omega$$. The error in the measurement of the potential difference in volts approximately is :

A
$$0.01$$

B
$$0.02$$

C
$$0.03$$

D
$$0.05$$

Solution
Question 6
1 / -0

If $${i_1} = 3\sin \omega t\,and\,{i_2} = 4\cos \omega t$$, then $$i_3$$ is

A
$$5\sin \left( {\omega t + {{53}^ \circ }} \right)$$

B
$$5\sin \left( {\omega t + {{37}^ \circ }} \right)$$

C
$$5\sin \left( {\omega t + {{45}^ \circ }} \right)$$

D
$$5\cos \left( {\omega t - {{53}^ \circ }} \right)$$

Solution
Question 7
1 / -0

Two resistors $$R_1 \, (24 \pm 0.5) \Omega$$ and $$R_2 \, (8 \pm 0.3) \Omega$$ are joined in series. The equivalent resistance is

A
$$32 \pm 0.33 \Omega$$

B
$$32 \pm 0.8 \Omega$$

C
$$32 \pm 0.2\Omega$$

D
$$32 \pm 0.5 \Omega$$

Solution

R₁ = 24 ± 0.5

R₂ = 8 ± 0.3

In series R₁+ R₂ = 32 ± 0.8
Question 8
1 / -0

The post office box works on the principle of :

A
Potentiometer

B
Principle of wheat stone bridge

C
Matter waves

D
Ampere's law

Solution
Question 9
1 / -0

Equivalence Resistance?

A
2R

B
5R

C
3R

D
7R

Solution
Question 10
1 / -0

The inductance of a coil is $$L = 10 H$$ and resistance $$R = 5 \Omega$$. If applied voltage of battery is $$10 V$$ and it switches off in $$1$$ millisecond, find induced electromotive force of inductor.

A
$$2 \times 10^4 V$$

B
$$1.2 \times 10^4 V$$

C
$$2 \times 10^{-4} V$$

D
None of these

Solution

According to question.....................
$$\begin{array}{l} \varphi =Li \\ or,\, \, \, e-\frac { { d\varphi } }{ { dt } } =-\frac { d }{ { dt } } (Li) \\ or,\, \, \, e=-L\frac { { di } }{ { dt } } \\ Induced\, current\, =\frac { V }{ R } =\frac { { 10 } }{ 5 } =2A \\ Circuit\, \, switches\, \, off\, in\, \, 1\, milli{ { second } } \\ or,\, \, \, dt=1\times { 10^{ -3 } }s \\ and,\, \, \, L=10H \\ \therefore \, \, \, \, Induced\, emp\, in\, \, inductor\, is\, \left| e \right| =10\times \frac { 2 }{ { 1\times { { 10 }^{ -3 } } } } =2\times { 10^{ 4 } }V \\ so\, the\, \, option\, \, is\, \, A.\, \end{array}$$