21. What is the SI unit of wavelength?
a) Meter
b) Hertz
c) Joule
d) Newton
Answer: a) Meter
22. What is the formula for torque?
a) T = Fd
b) T = Fr sin θ
c) T = mgh
d) T = QV
Answer: b) T = Fr sin θ
23. Which of the following is an example of a non-renewable energy source?
a) Solar energy
b) Wind energy
c) Coal
d) Hydroelectric energy
Answer: c) Coal
24. What is the process by which an atom loses or gains electrons called?
a) Ionization
b) Radiation
c) Conduction
d) Induction
Answer: a) Ionization
25. What is the formula for electric power?
a) P = IV
b) P = I²R
c) P = V²/R
d) P = QV
Answer: a) P = IV
