A wire 0.2 m long carries 2 A at right angles to a magnetic field of 0.2 T. What force acts on it?
Answer and explanation
Correct answer: C. 0.08 N
- Step 1: F = BIL sin θ, with sin 90° = 1. Step 2. F = 0.2 × 2 × 0.2 = 0.08 N. Answer: 0.08 N. Why not the others: 0.4 N is what you get if you forget the length. 2 N is what you get if you divide by B. 0.8 N is what you get if you misplace a power of ten.
Practise more Mechanics, waves and electricity.
Free questions with an explanation for every one, and full timed WBJEE mock tests.
More Mechanics, waves and electricity questions
- What force gives a mass of 9 kg an acceleration of 9 m/s²?
- What is the kinetic energy of a 20 kg body moving at 4 m/s?
- How much gravitational potential energy does a 2 kg mass gain when lifted 11 m? (take g = 10 m/s²)
- A machine takes in 800 J of energy and gives out 600 J of useful work. What is its efficiency?
- What is the pressure due to a column of liquid of density 800 kg/m³ and depth 10 m? (take g = 10 m/s²)
- A resistor of 2 Ω carries a current of 5 A. What is the potential difference across it?