Start learning →

MHT-CET Magnetic Fields due to Electric Current — practice questions

Explore 43 free Magnetic Fields due to Electric Current questions in MHT-CET Physics. Open each question or exercise to read its content, reference answers and available explanation.

Practise Magnetic Fields due to Electric Current with Quill →

Magnetic Fields due to Electric Current questions and exercises with answers

Showing questions 1–30 of 43.

The Biot-Savart law gives the field of a current element as varying with distance r as:Read the answer and worked solution →A long straight wire carries 5 A. What is the magnetic field at 10 cm from it?Read the answer and worked solution →Doubling the distance from a long straight current-carrying wire changes its magnetic field to:Read the answer and worked solution →The magnetic field at the centre of a circular loop of radius R carrying current I is:Read the answer and worked solution →A circular arc of radius R subtends angle theta at its centre and carries current I. The field at the centre is:Read the answer and worked solution →The force per unit length between two long parallel wires with currents I1, I2 at distance d is:Read the answer and worked solution →Two parallel wires carry 10 A and 5 A, 5 cm apart. The force per metre is:Read the answer and worked solution →The SI ampere is defined using parallel wires 1 m apart in vacuum with a force per metre of:Read the answer and worked solution →Doubling the separation of two parallel current-carrying wires changes the force between them to:Read the answer and worked solution →Two wires 0.2 m apart carry 20 A and 30 A. What is the force per metre?Read the answer and worked solution →By Ampere's law, the closed line integral of B equals:Read the answer and worked solution →In magnetostatics, Ampere's law plays the role that which law plays in electrostatics?Read the answer and worked solution →The Biot-Savart law in magnetostatics is analogous to which law in electrostatics?Read the answer and worked solution →From which law can Ampere's law be derived?Read the answer and worked solution →Three wires carry 2 A and 3 A out of a page and 4 A into it, all inside a loop. The integral of B.dl is:Read the answer and worked solution →A wire outside an Amperian loop contributes what to the closed line integral of B?Read the answer and worked solution →An ideal solenoid has n turns per unit length and current i. Its inside field is:Read the answer and worked solution →The magnetic field outside an ideal long solenoid is:Read the answer and worked solution →A 0.5 m solenoid has 400 turns and carries 2.5 A. The inside field is about:Read the answer and worked solution →A solenoid carrying 5 A has a field 6.28 x 10^-3 T. How many turns per metre does it have?Read the answer and worked solution →Doubling the current in a solenoid while halving its turns per unit length makes B:Read the answer and worked solution →Inside a long ideal solenoid the magnetic field is directed:Read the answer and worked solution →A toroid is best described as:Read the answer and worked solution →The magnetic field lines inside a toroid form:Read the answer and worked solution →In a coaxial cable with equal opposite currents, the field outside the outer conductor is:Read the answer and worked solution →In a coaxial cable, the field between the core (a) and outer shell (b) is:Read the answer and worked solution →At a point on the line along a current element, the field of that element is:Read the answer and worked solution →The field of a current element is largest at a point where the angle between dl and r is:Read the answer and worked solution →The direction of dB due to a current element is given by the vector:Read the answer and worked solution →A wire carries 20 A. At what distance is its field 4 x 10^-5 T?Read the answer and worked solution →

Worked practice questions

The Biot-Savart law gives the field of a current element as varying with distance r as:

  1. 1/r^3
  2. 1/r
  3. r^2
  4. 1/r^2
Show answer and solution

Correct answer: D. 1/r^2

The magnitude of dB is proportional to Idl sin(theta)/r^2, so it is an inverse square law in r.

Open this question →

A long straight wire carries 5 A. What is the magnetic field at 10 cm from it?

  1. 1 x 10^-6 T
  2. 5 x 10^-6 T
  3. 1 x 10^-5 T
  4. 2 x 10^-5 T
Show answer and solution

Correct answer: C. 1 x 10^-5 T

B = mu0 I/(2 pi r) = 2 x 10^-7 x 5/0.1 = 1 x 10^-5 T.

Open this question →

Doubling the distance from a long straight current-carrying wire changes its magnetic field to:

  1. four times
  2. double
  3. one fourth
  4. half
Show answer and solution

Correct answer: D. half

For a long wire B = mu0 I/(2 pi r), so B is inversely proportional to r and halves when r doubles.

Open this question →

How to practise

  1. Choose a Magnetic Fields due to Electric Current question and try to work out your answer.
  2. Open the question to check the correct answer and read its worked solution.
  3. Continue in the app for bite-sized lessons, explanations and review with Quill. You can start without creating an account.

More Physics topics

ElectrostaticsCurrent ElectricityOscillationsElectromagnetic InductionKinetic Theory of GasesMechanical Properties of FluidsAtomsWave Optics