Tutorial 9 — Magnetism (Subtopics 4-5) & Electromagnetic Induction
Course: FAD1022 Basic Physics 2
Semester: 2 2025/2026
Prepared by: Dr Aisyah Hartini Jahidin & Sir Naharudin
Question 1
A long wire with a radius of 8 mm carries a current of 10 A.
Calculate the magnetic field:
a) Inside the wire, at a point 2.5 mm below the wire's surface b) At the surface of the wire
Question 2
A 3-turn rectangular coil with sides $d_1 = 35 \text{ mm}$ and $d_2 = 25 \text{ mm}$ carries a current of 2 A and is placed in a uniform magnetic field (Figure 1). The coil experiences a torque of $15 \text{ mN m}$.
Calculate:
a) The magnetic field strength (mT) b) Determine the direction of rotation of the coil
Question 3
A rectangular loop abcd carries a current of 1.85 A and is placed in a uniform magnetic field of 0.15 T (Figure 2). The plane of the loop makes an angle of $23°$ with the magnetic field.
Dimensions:
- Sides: 3.5 cm and 6 cm
Calculate:
a) The torque acting on the loop b) State the direction of rotation of the loop
Question 4
A 50-loop circular coil has a radius of 3.0 cm. It is oriented so that the field lines of a magnetic field are normal to the area of the coil. Suppose the magnetic field is varied so that B increases from 0.10 T to 0.35 T in 2.0 milliseconds.
Calculate the average induced emf in the coil.
Question 5
In Figure 3(a) there is a magnetic field in the +x-direction, with $B = 0.20 \text{ T}$ and a loop of wire in the yz-plane. The loop has an area of $5.0 \text{ cm}^2$ and rotates about line CD as axis. Point A rotates toward positive x-values from the position shown.
If the loop rotates through $50°$ from its indicated position (Figure 3(b)), in a time of 0.20 s, calculate the initial and final magnetic flux.
Related Concepts
- Magnetism
- Magnetic Field Inside Wire ($B = \frac{\mu_0 Ir}{2\pi R^2}$)
- Torque on Current Loop ($\tau = NIAB\sin\theta$)
- Magnetic Dipole Moment ($\mu = NIA$)
- Electromagnetic Induction
- Faraday's Law ($\varepsilon = -N\frac{d\Phi_B}{dt}$)
- Magnetic Flux ($\Phi_B = BA\cos\theta$)
- Lenz's Law
- Induced EMF