Electricity Test

Result

Electricity Test - 76

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

In the adjoining figure the equivalent resistance between $$A$$ and $$B$$ is

A
$$5\ \Omega $$

B
$$8\ \Omega $$

C
$$2.5\ \Omega $$

D
$$6.8\ \Omega $$

Solution

We are given circuit, we have to calculate equivalent between A and B.
Clearly in 2nd fig.
2, 2 and 2 are in series
So, $$R_1 = 2 + 2 + 2$$
$$= 6\Omega$$
Now, $$6\Omega$$ and $$6\Omega$$ are in parallel
$$\therefore R_2 = \dfrac{6\times 6}{12} = 3\Omega$$
Now, Equivalent Resistance ($$R_{AB}$$) = 1 + 3 + 1
$$= 5\Omega$$
Hence option A is correct.
Question 2
1 / -0

Three equal resistors are connected as shown in figure. the maximum power consumed by each resistor is 18 W. Then the maximum power consumed by the combination is :

A
$$18 W$$

B
$$27 W$$

C
$$36 W$$

D
$$54 W$$

Solution

equivalent resistance from $$A\rightarrow B$$

$$\boxed{(R\parallel R)+R}$$

$$\Rightarrow \dfrac{1}{\dfrac{1}{R}+\dfrac{1}{R}}+R=\dfrac{1}{\dfrac{2}{R}}+R=\dfrac{R}{2}+R$$

$$=\dfrac{3R}{2}$$

$$\therefore$$ equivalent resistance $$=\dfrac{3R}{2}$$
Power across the single resistor $$=18\ W$$ ( given)

$$P=i^2R=18\ W.......(1)$$

Power across the equivalent circuit is

$$P_1=i^2\times \dfrac{3R}{2}=\dfrac{3i^2R}{2}\rightarrow .....(2)$$

dividing $$(1)$$ by $$(2)$$

$$\dfrac{P}{P_1}=\dfrac{18}{P_1}=\dfrac{i^2R}{\dfrac{3i^2R}{2}}=\dfrac{2}{3}$$

$$\Rightarrow P_1=\dfrac{3}{2}\times 18=27\ W$$
$$\therefore$$ maximum power consumed by circuit $$=27\ W$$
Question 3
1 / -0

Effective resistance between $$A$$ and $$B$$ is

A
$$6\Omega$$

B
$$3\Omega$$

C
$$\dfrac {2}{3}\Omega$$

D
$$\dfrac {3}{2}\Omega$$

Solution
Question 4
1 / -0

As we continue to flow the current through the human body then

A
Its resistance gradually decrease.

B
Its resistance gradually increases.

C
Its resistance remains same.

D
any of these.

Solution

As we continue to flow the current through the human body, the potential difference increases so from Ohm's law ( V= IR) the resistance of the body gradually decreases.
Question 5
1 / -0

A hollow cylinder $$(\rho =2.2\times 10^{-8}\Omega -m)$$ of length 3m has inner and outer diameter as 2mm and 4mm respectively. The resistance of the cylinder is

A
$$0.35\times 10^{-3}\Omega $$

B
$$3\times 10^{-3}\Omega $$

C
$$7\times 10^{-3}\Omega $$

D
none of these

Solution

outer radii$$=2=R$$
inner radii$$1=r$$
$$l=3m$$
$$p=2.2\times 10^{-8}\Omega-m$$
$$resistance=resistivity\left(\dfrac{lenght}{area}\right)$$
Area of hollow cylinder$$=\pi(R^2-r^2)$$
$$=\pi (2^{ 2 }-1^{ 2 })=3.14\times 3\times 10^{ -6 }=9.42\times { 10 }^{ -6 }$$

$$R=2.2\times 10^{ -8 }\left[ \dfrac { 3 }{ 9.42\times { 10 }^{ -6 } } \right] $$
$$R=0.7\times 10^{-2}\Omega$$
$$R=7\times 10^{-3}\Omega$$
Question 6
1 / -0

In the following circuit, what is equivalent resistance between A and B points?

A
$$3\Omega$$

B
$$6\Omega$$

C
$$1.5\Omega$$

D
$$2\Omega$$

Solution
Question 7
1 / -0

In the circuit shown, when R has removed an additional resistance of $$72\ \Omega $$ must be introduced in series with the battery in order to keep the current through $$30\ \Omega $$ resistance unaltered. Hence R is

A
$$15\ \Omega $$

B
$$18\ \Omega $$

C
$$25.7\ \Omega $$

D
$$21\ \Omega $$
Question 8
1 / -0

The value of the resistance $$r$$ in the electric circuit given below is (in $$\Omega$$)

A
$$2$$

B
$$5$$

C
$$1$$

D
$$3$$

Solution
Question 9
1 / -0

5 identical thin conducting plates are kept parallel to each other such that separation between each plate is d. Area of each plate is A. Plates are arranged as shown in figure. All wires are conducting.
Switch S is closed, find the work done by battery. $$\left( A\succ \succ \succ { d }^{ 2 } \right) $$

A
$$\dfrac { { \in }_{ 0 }{ AV }^{ 2 } }{ 5d } $$

B
$$\dfrac { 2{ \in }_{ 0 }{ AV }^{ 2 } }{ 5d } $$

C
$$\dfrac { 3{ \in }_{ 0 }{ AV }^{ 2 } }{ 2d } $$

D
$$\dfrac { 2{ \in }_{ 0 }{ AV }^{ 2 } }{ d } $$

Solution
Question 10
1 / -0

In the given circuit (as shown in the figure), choose the wrong statement.

A
The equivalent resistance between $$C$$ and $$G$$ is $$3\ K\Omega$$

B
The current provided by the source is $$4\ mA$$

C
The current provided by the source is $$8\ mA$$

D
Voltage across points $$G$$ and $$E$$ is $$4V$$

Solution