21.	A particle performs simple harmonic oscillations. Which of the following quantities will be unaffected by a reduction in the amplitude of oscillations?
A.	The total energy
B.	The maximum speed
C.	The maximum acceleration
D.	The period

22.	Which graph correctly shows how the acceleration, a of a particle undergoing SHM varies with its displacement, x from its equilibrium position?

 
23.	A mass on the end of a horizontal spring is displaced from its equilibrium position by a distance A and released. Its subsequent oscillations have total energy E and time period T.
		
	An identical mass is attached to an identical spring. The maximum displacement is 2A. Assuming this spring obeys Hooke’s law, which of the following gives the correct time period and total energy?

	New time period	New energy	
A.	T	4E	
B.	T	2E	
C.		4E	
D.		2E	

24.	In which of the following regions of the electromagnetic spectrum is radiation of wavelength 600 nm located?
A.	microwaves
B.	radio waves
C.	visible light
D.	X-rays

25.	What is the best estimate for the refractive index of a medium in which light travels at a speed of 2.7 × 108 m s–1?
A.	0.9
B.	1.0
C.	1.1
D.	2.7

28.	A wave pulse is travelling to the right along a string.
		
	Which of the following best represents the direction of the velocity of the point P?
A.	↑
B.	↓
C.	→
D.	←

30.	Diagram 1 represents equally spaced beads on a spring. The beads are 1 cm apart.
	Diagram 1

	A longitudinal wave propagates along the spring. Diagram 2 shows the position of the beads at a particular instant.
	Diagram 2

	Which of the following is the best estimate of the wavelength?
A.	2 cm
B.	4 cm
C.	8 cm
D.	16 cm