Physics

Current Electricity and Circuits

450 Questions

Current electricity and circuits questions cover resistors, EMF, internal resistance, and power calculations in series and parallel configurations. Solving these builds a strong understanding of electrical principles and circuit analysis. These physics problems are highly relevant for technical and science aptitude tests.

Resistor combinationsPower dissipationEMF and internal resistanceAC circuit analysisOperational amplifiers

Current Electricity and Circuits Questions

Multiple choice physics electric circuits combination of resistors combination of cells combinations of components


A cell of constant emf first connect to a resistance $R _1$ and then to connected to the resistance $R _2.$ If power delivered in both cases in the same then internal resistance of the cell

  1. $\dfrac { R _ { 1 } - R _ { 2 } } { 2 }$
  2. $ { R _ { 1 } + R _ { 2 } } $
  3. $\sqrt { R _ { 1 } R _ { 2 } }$
  4. $\sqrt { R _ { 1 } + R _ { 2 } / 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The cell has constant emf$,$

Resistance is $R _1$ and $R _2$

$P = V _2 / R _1 + r$

$P = V _2 / R _2 - r$

$( R _1- R _2 ) / 2$

The internal resistance of the cell is $( R _1 - R _2 ) / 2$

Hence,

option $(A)$ is correct answer.

Multiple choice physics electric circuits combination of resistors combination of cells combinations of components

A battery is delivering same power to resistance $R _1$ and $R _2$ . Then find the internal resistance of battery :

  1. $\dfrac { R _ { 1 } - R _ { 2 } } { 2 }$
  2. ${ R _ { 1 } + R _ { 2 } }$
  3. $ \sqrt { R _ { 1 } + R _ { 2 } }$
  4. $\sqrt { R _ { 1 } + R _ { 2 } / 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
$\begin{array}{l} P=\frac { { { V^{ 2 } } } }{ { { R^{ 2 } }+r } } -------\left( 1 \right)  \\ P=\frac { { { V^{ 2 } } } }{ { { R^{ 2 } }-r } } -------\left( 2 \right)  \\ solve\, \, eqation\left( 1 \right) and\left( 2 \right)  \\ =\dfrac { { { R _{ 1 } }-{ R _{ 2 } } } }{ 2 }  \end{array}$
Hence,
option $(A)$ is correct answer.
Multiple choice physics electric current and its effects electric bell the magnetic effect of a current current electricity and magnetism

An electric bell has a resistance of $5 \Omega$ and requires a current of $0.25\ A$ to work it. Assuming that the resistance of the bell wire is $1 \Omega$ per $15m$ and that the bell push is $90m$ distance from the bell. How many cells each of emf $1.4V$ and internal resistance $2 \Omega$, will be required to work the circuit.

  1. $3$
  2. $4$
  3. $5$
  4. $Can't\ be\ determined$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total resistance = R_bell + R_wire = 5 + (90/15)*1 = 11 ohms. Current = 0.25A. Total EMF required = I * R_total = 0.25 * (11 + n*r_internal). Solving for n with 1.4V cells.

Multiple choice safety precautions to be taken while handling electricity ohm's law electric charge and electric current current electricity physics

Ohm's law in vector form is :

  1. $V=I.R$
  2. $\overrightarrow { J } =\sigma \overrightarrow { E } $
  3. $\overrightarrow { J } =\rho \overrightarrow { E } $
  4. $\overrightarrow { E } =\sigma \overrightarrow { J } $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ohm's law in vector form relates current density J to electric field E via conductivity sigma: J = sigma * E.

Multiple choice physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

Kirchoffs law of junctions is also called the law of conservation of:

  1. Energy

  2. Charge

  3. Momentum

  4. Angular momentum
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Kirchoff's second law:- According to the law, at a particular junction the charge entering the junction is equal to charge exiting that junction.
$ \Rightarrow$ There is no charge accumulated at junction. This is also called as law of conservation of charge.

Multiple choice physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

Between any two points in a circuit, the sum of all .............. is the same through any pathway.

  1. charge

  2. current

  3. potential difference

  4. resistance
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Kirchhoff's voltage law says that if we add up all the voltage drops that occur around the loop, the total will be equal to the total voltage applied across the loop.hence between any two point in the circuit , the sum of all the voltage drops is the same through any pathway.

Multiple choice physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

For a $DC$ circuit, Kirchoff's rules yield the following equations.
$I _{3}=I _{1}+I _{2}$
$10 = 3I _{1}-2I _{2}$
$50=2I _{2}+9.6I _{3}$
What is the current $I _{2}$ (Amps)?

  1. $0.131$
  2. $-1.37$
  3. $0.245$
  4. $-3.5$
  5. $1.00$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Given: 1) I3 = I1 + I2, 2) 10 = 3I1 - 2I2, 3) 50 = 2I2 + 9.6I3. Substitute (1) into (3): 50 = 2I2 + 9.6(I1 + I2) = 9.6I1 + 11.6I2. Now solve the system: 3I1 - 2I2 = 10 (multiply by 3.2: 9.6I1 - 6.4I2 = 32). Subtract from 9.6I1 + 11.6I2 = 50: (11.6 + 6.4)I2 = 50 - 32 => 18I2 = 18 => I2 = 1.0 A.

Multiple choice physics kirchhoff's law circuit problems kirchoff's law and problems on it equivalent resistance in series and parallel connection

Kirchoffs 1st and 2nd laws are based on conservation of

  1. Energy and charge respectively

  2. Charge and energy respectively

  3. Mass and charge respectively

  4. None of these above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Kirchhoff's $1$st law states that the total amount of current coming at a junction must be equal to the total amount of current going away from it i.e. the total charge must be conserved. Thus Kirchhoff's $1$st law is based on the conservation of charge.

Kirchhoff's $2$nd law states that the sum of the potential drop across all the components in a loop must be zero. Thus Kirchhoff's $2$nd law is based on the conservation of energy.

Multiple choice physics kirchhoff's law combination of resistors combination of cells combinations of components

The diagram shows a $40\Omega$ resistor and a $60\Omega$ resistor connected in parallel.
What is the total resistance between points P and Q?

  1. less than $40\Omega$
  2. $50\Omega$
  3. between $50\Omega$ and $100\Omega$
  4. $100\Omega$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
For parallel connection
$R _{eq}= \dfrac{R _1 \times R _2}{R _1 +R _2}$
$\implies R _{eq}= \dfrac{40 \times 60}{40+60}$
$\implies R _{eq}= 24 \Omega$

So, it is less than $40 \Omega$
Multiple choice properties of an ideal op-amp electronics physics the operational amplifier (op-amp)

An infinite impedance for an ideal opamp implies

  1. Opamp doesn't draw any current through its terminals

  2. Opamp draws only 10 micro amperes for its function

  3. Opamp's inverting terminal draws no current

  4. Opamp's non inverting terminal draws no current
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since input impedance for an ideal opamp is infinite, the current drawn will be zero 

Multiple choice physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

Joule's heating effect is

  1. Reversible

  2. Irreversible

  3. Both

  4. None
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Joule heating effect is irreversible that means if the direction of current in a resistor is reversed, the cooling of resistor does not occur whereas heating of the resistor takes place.

Heat produced via Joule's heating effect    $H = i^2Rt$ 

Multiple choice physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

 When electric current is passed through conductor i.e. generates heat due to resistance it offers to current flow. What this phenomena known as :

  1. Burning effect of electricity

  2. Potential Effect of electricity

  3. Heating effect of electricity

  4. Floating effect of electricity
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The phenomenon of generating heat due to the resistance of the conductor when a current passes through it is known as heating effect of electricity.

Heat produced     $H = I^2Rt$

Multiple choice physics effects of electric current joule's law of heating thermal effect of electric current heating effect of electric current

Which of the following statement is correct?

  1. seebeck effect is irreversible.

  2. Thomson effect is localised at the junction.

  3. Joule heating effect is indeoendent of the direction of flow of current in a conductor.

  4. Thomson effect is similer in origin to pelteir effect. They both are due to non-uniform distribution of electrons in a metal.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Joule heating (also referred to as resistive or ohmic heating) describes the process where the energy of an electric current is converted into heat as it flows through a resistance.

In particular, when the electric current flows through a solid or liquid with finite conductivity, electric energy is converted to heat through resistive losses in the material. The heat is generated on the microscale when the conduction electrons transfer energy to the conductor's atoms by way of collisions. It does not depend upon the direction of flow of current, but its amount.