EASY

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$I - t$ curve is shown in figure then find the total charge from $t = 2$ to $t = 8 : -$

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Important Questions on Current Electricity

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A conducting wire of length $l$ , area of cross-section $A$ and electric resistivity $ρ$ is connected between the terminals of a battery. A potential difference $V$ is developed between its ends, causing an electric current. If the length of the wire of the same material is doubled and the area of cross-section is halved, the resultant current would be___

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

The current in a conductor varies with time

t

I = 2 t + 3 t^{2}

, where

I

is in ampere and

t

in seconds. Electric charge flowing through a section of the conductor during

t = 2 \sec

t = 3 \sec

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A current through a wire depends on time as

i = α_{0} t + β t^{2}

, where

α_{0} = 20 A s^{- 1}

and

β = 8 A s^{- 2}

. Find the charge crossed through a section of the wire in

15 s .

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Electric Current

An electric cable having a resistance $R$ delivers $11 kW$ of power at $220 V$ to a factory. If the efficiency of transmission is $91 %$ , then what is the value of $R$ ?

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A conductor carries a current of

300 mA

. The number of electrons passing through it in

1

minute are ___ .

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A heating coil of resistance $100 Ω$ takes $100 s$ to boil certain amount of water. If a similar heating coil is connected in series with the heating coil, then the time required to boil the water is $t_{s}$ , while $t_{p}$ time is required to boil the same amount of water if the coils are connected in parallel. What will be $\frac{t_{s}}{t_{p}}$ ?

HARD

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A solar cell is to be fabricated for efficient conversion of solar radiation to emf using material

A .

The solar cell is to be mechanically protected with the help of a coating using material

B .

If the band gap energy of materials

A

and

B

are

E_{A}

and

E_{B}

respectively, then which of the following choices is optimum for better performance of the solar cell.

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Electric Current

Three resistors having resistances $r_{1}, r_{2}$ and $r_{3}$ are connected as shown in the given circuit. The ratio $\frac{i_{3}}{i_{1}}$ of currents in terms of resistances used in the circuit is :

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MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A circular wire has current density

J = (2 \times 10^{10} \frac{A}{m^{2}}) r^{2}

where

r

is the radial distance, out of the wire radius is

2 mm

. The end-to-end potential applied to the wire is

50 V

. How much energy (in joule) is converted to thermal energy in

100 s

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

Estimate the magnitude of current that passes through a wire, if

0.1 mol

of electrons flow through it in

40 \min

. (Assume Avogadro number

= 6 \times 10^{23}

)

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A resistor develops

800 J

of thermal energy in

20 s

when a current of

4 A

is passed through it. If the current is increased from

4 A

8 A

, what will be the energy developed in

20 s

HARD

Physics>Electricity and Magnetism>Current Electricity>Electric Current

Shown in the figure is a semicircular metallic strip that has thickness $t$ and resistivity $ρ$ . Its inner radius is $R_{1}$ and outer radius is $R_{2}$ . If a voltage $V_{0}$ is applied between its two ends, a current $I$ flows in it. In addition, it is observed that a transverse voltage $Δ V$ develops between its inner and outer surfaces due to purely kinetic effects of moving electrons (ignore any role of the magnetic field due to the current). Then (figure is schematic and not drawn to scale)

Question Image

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

Solar energy of

200 {Wm}^{- 2}

is incident on a horizontal surface. If

20 %

of this energy can be converted into useful electrical energy, the area needed to supply

8 kW

energy is

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is:

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Electric Current

A current of

5 A

is passing through a non-linear magnesium wire of cross-section

0.04 m^{2}

. At every point the direction of current density is at an angle of

60 °

with the unit vector of area of cross-section.
The magnitude of electric field at every point of the conductor is: (resistivity of magnesium

ρ = 44 \times 10^{- 8} Ωm

)

EASY

Physics>Electricity and Magnetism>Current Electricity>Electric Current

The unit of current element is

MEDIUM

Physics>Electricity and Magnetism>Current Electricity>Electric Current

The current flowing through a wire depends on time as $I = 3 t^{2} + 2 t + 5 .$ The charge flowing through the cross section of the wire in time from $t = 0$ to $t = 2 s$ is