Current Electricity Test

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Current Electricity Test - 27

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Question 1
1 / -0

The common dry cell produces a voltage of:

A
$$1.5 V$$

B
$$30 V$$

C
$$60 V$$

D
$$3 V$$

Solution

A common dry cell is a type of electricity producing chemical cell , commonly used today for many home and portable devices, often in form of batteries.
By standards, a common dry cell has a constant voltage of $$1.5V$$.Hence correct option is A.
Question 2
1 / -0

A given resistor has the following colour scheme of the various strips on it : Brown, black, green and silver. Its value in ohm is :

A
$$1.0 \times 10^4 \pm 10\%$$

B
$$1.0 \times 10^5 \pm 10\%$$

C
$$1.0 \times 10^6 \pm 10\%$$

D
$$1.0 \times 10^7 \pm 10\%$$

Solution

Numbers attached for brown, black, green and silver are $$1, 0, 5, \pm10\%$$. Therefore the resistance of given resistor
$$= 10 \times 10^5\ \Omega \pm 10\%$$.
Question 3
1 / -0

Why is the Wheatstone bridge better than the other methods of measuring resistances?

A
It does not involve Ohm's law

B
It is based on Kirchoff's law

C
It has four resistor arms

D
It is a null method

Solution

The Wheatstone bridge is used to measure the unknown resistance by using null method. i.e, when the bridge is balanced, no current through the galvanometer. Using this null method, we can easily measure the unknown resistance if the other three arm's resistor are given.
Question 4
1 / -0

Name the instrument used to control the current in an electric circuit.

A
Rheostat

B
Voltmeter

C
Ammeter

D
Galvanometer

Solution

Rheostat is the instrument used to control the current in an electric circuit.
It is an adjustable or variable resistor. It is used to control the electrical resistance of a circuit without interrupting the flow of current. Rheostat has 3 terminals and usually consist of a resistive wire wrapped to form a toroid coil with a wiper that slides along the surface of the coil. It is most often designed with a ceramic core. Rheostats are used in applications that require high voltage and current.
The rheostat can adjust generator characteristics, dim lights, and start or control the speed of motors. Its resistance element can be a metal wire or ribbon, carbon, or a conducting liquid, depending on the application.
Question 5
1 / -0

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

A
$$0A$$

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

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

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

Solution

Using Kirchoff's current law, which states that the net current in a junction is zero
the let The magnitude of the current in the portion $$PQ$$ is $$x$$ and the direction P to Q.
$$x=-3A+1A-2A-8A+4A+2A$$
$$x=-13A+7A= - 6A$$
hence,the magnitude of the current in the portion $$PQ$$ is $$6A$$ and the direction from $$Q$$ to $$P$$.
Question 6
1 / -0

When a 1 ohm resistor is connected across the potential difference of 20 V, what will be power dissipation in it?

A
$$200 W$$

B
$$20 W$$

C
$$400 W$$

D
$$10 W$$

Solution

Given : $$V = 20$$ volts $$R =1\Omega$$
Power dissipated in it $$P =\dfrac{V^2}{R} = \dfrac{20^2}{1} = 400$$ W
Question 7
1 / -0

The current in the primary circuit of a potentiometer wire is 0.5 A, $$\rho$$ for the wire is $$4 \times 10^{-7} \Omega -m$$ and area of cross-section of wire is $$8 \times 10^{-6} m^2$$. The potential gradient in the wire would be

A
25 mV/meter

B
2.5 mV/meter

C
25 V/meter

D
10 V/meter

Solution

Potential gradient of wire $$= \displaystyle \dfrac{V}{l} = \left ( \dfrac{\rho}{A} \right ) \times I$$ where $$l\ \&\ A$$ are the length and cross-section of wire so $$\displaystyle \dfrac{V}{l} = \frac{4 \times 10^{-7}}{8 \times 10^{-6}} \times 0.5 = 25\ mV/meter$$
Question 8
1 / -0

A cell is used to :

A
measure current in a circuit.

B
provide current in a circuit.

C
check current in a circuit.

D
prevent current in a circuit.

Solution

A cell stores energy in chemical form in it's active materials and can convert this energy into electric energy on demand. typically by means of a redox reaction. the chemical energy when in form of electrical energy flows in form of current in electric circuits. Hence correct option is option B.
Question 9
1 / -0

E.M.F. ofa cell is expressed in

A
volt

B
volt per metre

C
volt metre

D
none of these

Solution

E.m.f of a cell is defined as the maximum potential difference across the cell when no current flows through the circuit.
Hence e.m.f is expressed in volt $$(V)$$.
Question 10
1 / -0

The unit of e.m.f. of a cell is:

A
dyne

B
volt

C
ampere

D
joule

Solution

Electromotive force or e.m.f is defined as the battery's energy per Coulomb of charge passing through it. like other measures of energy per charge emf has SI unit of volts , equivalent to joules per coulomb.

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Re-Attempt Weekly Quiz Competition

Current Electricity Test - 27

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Current Electricity Test - 27

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SHARING IS CARING

Question 1

$$1.5 V$$

$$30 V$$

$$60 V$$

$$3 V$$

Solution

Question 2

$$1.0 \times 10^4 \pm 10\%$$

$$1.0 \times 10^5 \pm 10\%$$

$$1.0 \times 10^6 \pm 10\%$$

$$1.0 \times 10^7 \pm 10\%$$

Solution

Question 3

It does not involve Ohm's law

It is based on Kirchoff's law

It has four resistor arms

It is a null method

Solution

Question 4

Rheostat

Voltmeter

Ammeter

Galvanometer

Solution

Question 5

$$0A$$

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

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

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

Solution

Question 6

$$200 W$$

$$20 W$$

$$400 W$$

$$10 W$$

Solution

Question 7

25 mV/meter

2.5 mV/meter

25 V/meter

10 V/meter

Solution

Question 8

measure current in a circuit.

provide current in a circuit.

check current in a circuit.

prevent current in a circuit.

Solution

Question 9

volt

volt per metre

volt metre

none of these

Solution

Question 10

dyne

volt

ampere

joule

Solution

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