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 units and measurement: error analysis significant figures significant figures and rounding of digits units and measurements

Two resistances $r _1=(5.0\pm 0.2)\Omega$ and $r _2=(10.0\pm 0.1)\Omega$ are connected in parallel. Find the value of equivalent resistance with limits of percentage error.

  1. $r _p=4\Omega\pm $7%
  2. $r _p=3.3\Omega\pm $14%
  3. $r _p=3.3\Omega\pm $3.5%
  4. $r _p=3.3\Omega\pm $7%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Here, $r _1=5 \Omega , r _2=10 \Omega, \Delta r _1=0.2 \Omega $ and $\Delta r _2=0.1 \Omega$


The equivalent resistance, $r _p=\dfrac{r _1r _2}{r _1+r _2}=\dfrac{5\times 10}{5+10}=3.3 \Omega$

$\dfrac{\Delta r _p}{r _p} = \dfrac{\Delta r _1}{r _1}+\dfrac{\Delta r _2}{r _2}+\dfrac{\Delta (r _1+r _2)}{r _1+r _2}=\dfrac{0.2}{5}+\dfrac{0.1}{10}+\dfrac{0.2+0.1}{5+10}=0.07$

Thus, The value of equivalent resistance with limits of  % error $=r _p\pm\Delta r _p=3.3 \Omega \pm 7 \%$

Multiple choice physics electric current, potential difference and resistance drift velocity and mobility drift speed drift velocity & mobility

A current of $5A$ passes through a copper conductor $(resistivity=1.7\times10^{-8}\Omega m$) of radius of cross-section $5mm$. Find the mobility of the charges if their drift velocity is $1.1\times 10^{-3}m/s$

  1. $1.3m^2/Vs$
  2. $1.5m^2/Vs$
  3. $1.8m^2/Vs$
  4. $1.0m^2/Vs$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\mu=\dfrac{V _d}{E}$     $E=\rho J$


$=\dfrac{1.1\times 10^{-3}}{1.7\times 10^{-8}\times \dfrac{5}{\pi \times 25\times 10^{-6}}}$

$=\dfrac{1.1\times 10^{-3}\times \pi \times 25\times10^{-6}}{1.7 \times 10^{-8} \times5}\approx 1.01m^2/Vs$

Multiple choice physics electric current, potential difference and resistance drift velocity and mobility drift speed drift velocity & mobility

The electric current in a wire may be calculated using the equation $I=Anvq$.
Which statement is not correct?

  1. n is the number of charge carriers per unit volume of the wire

  2. nA is the number of charge carriers per unit length of the wire

  3. q is the charge of each charge carrier

  4. v is the velocity of each charge carrier
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given that,

Electric current in the wire  , $I=Anvq$

Here $A$ is the cross-section of wire 
$n$ is the number of charge carriers per unit volume of wire
$v $ is  drift velocity of charge carriers 
$q$ is the charge of each charge carier 

Hence incorrect statement is $(D)$

Multiple choice physics electro-magnetism applications of electromagnets transformer transformers

The AC produced in India changes Its direction in every:

  1. $\displaystyle \frac{1}{100}$ second

  2. 100 second

  3. 50 second

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

Answer is A.

The rate at which alternating current reverses direction is called its frequency, expressed in hertz. Thus, standard household current in India is 50 Hz. AC electricity alternates back-and-forth in direction 50 times per second, according to the electrical system in the country. The charge at the ends of the wire alternates between negative (-) and positive (+). If the charge is negative (-), that pushes the negatively charged electrons away from that terminal. If the charge is positive (+), the electrons are attracted in that direction. Thus the electricity in the wire moves in one direction for a short while and then reverses its direction when the generator armature is in a different position. The direction changes twice in each cycle so that change of direction takes place after every 1/100 second.

Multiple choice

The SI unit of electric current is:

  1. Ampere

  2. Volt

  3. Ohm

  4. Coulomb
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The SI unit of electric current is Ampere, which represents the flow of one coulomb of charge per second.

Multiple choice

In an electrical circuit, the equation (L\frac{di}{dt} + Ri = E) describes the current (i) flowing through an inductor with inductance (L), a resistor with resistance (R), and a voltage source (E). What is the time constant of the circuit?

  1. \(\frac{L}{R}\)
  2. \(\frac{R}{L}\)
  3. \(\frac{E}{R}\)
  4. \(\frac{E}{L}\)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The time constant of the circuit is given by (\tau = \frac{L}{R}).

Multiple choice

What is the SI unit of electric current?

  1. Ampere

  2. Volt

  3. Ohm

  4. Coulomb
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The SI unit of electric current is the ampere (A), which is defined as the flow of one coulomb of charge per second.

Multiple choice

What is the relationship between voltage, current, and resistance in an electric circuit?

  1. Ohm's Law

  2. Kirchhoff's Current Law

  3. Kirchhoff's Voltage Law

  4. Faraday's Law
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ohm's Law states that the voltage across a conductor is directly proportional to the current flowing through it, provided the temperature and other physical conditions remain constant.

Multiple choice

What is the basic unit of charge in an electric circuit?

  1. Electron

  2. Proton

  3. Neutron

  4. Ion
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The basic unit of charge in an electric circuit is the electron, which carries a negative charge of 1.602 x 10^-19 coulombs.

Multiple choice

Which type of distribution system is characterized by multiple interconnected paths for power flow?

  1. Radial Distribution System

  2. Ring Distribution System

  3. Mesh Distribution System

  4. Hybrid Distribution System
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A mesh distribution system is a type of distribution system where power can flow through multiple interconnected paths, providing increased reliability and flexibility.

Multiple choice

Which type of distribution system is characterized by a combination of radial and ring structures?

  1. Radial Distribution System

  2. Ring Distribution System

  3. Mesh Distribution System

  4. Hybrid Distribution System
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A hybrid distribution system combines the features of radial and ring distribution systems, providing increased reliability and flexibility.

Multiple choice

How can smart grid data analytics improve grid reliability?

  1. By identifying potential grid vulnerabilities

  2. By optimizing grid maintenance and repair schedules

  3. By enhancing situational awareness for grid operators

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Smart grid data analytics contributes to improved grid reliability by identifying potential grid vulnerabilities, optimizing grid maintenance and repair schedules, and enhancing situational awareness for grid operators.

Multiple choice

What is the impedance of a transducer?

  1. The resistance of the transducer to the flow of electrical current

  2. The capacitance of the transducer

  3. The inductance of the transducer

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The impedance of a transducer is a measure of all of the above. It includes the resistance of the transducer to the flow of electrical current, the capacitance of the transducer, and the inductance of the transducer.

Multiple choice

Which type of electrical cable is commonly used for flexible connections between devices?

  1. BX cable

  2. Romex cable

  3. UF cable

  4. SO cord
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

SO cord (Service and Oil-Resistant cord) is designed for flexible connections between devices and is resistant to oil and moisture.

Multiple choice

In a series circuit, the total resistance is:

  1. Equal to the sum of individual resistances

  2. Less than the sum of individual resistances

  3. Greater than the sum of individual resistances

  4. Independent of the individual resistances
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In a series circuit, the total resistance is equal to the sum of the resistances of all the components connected in series.