OCR Physics A Level - Imaging and Signalling

The moon in this image (Iapetus) is 3900 pixels across and has a real world diameter of 1470 km. What is the resolution of the image?

• 380 m px^-1

• 376 km px^-1

• 0.380 m px^-1

• 380 km px^-1

A song is recorded with a sample rate of 44100 Hz with 16 bits per sample for each of the two stereo channels. Calculate the rate, in bytes per second, at which data is processed.

• 1411200 bytes s^-1

• 176400 bytes s^-1

• 88200 bytes s^-1

• 85600 bytes s^-1

The highest frequency in a film soundtrack is 6.0 kHz. The soundtrack is to be sampled and digitised. What should be the minimum sample rate?

• 24 kHz

• 3 kHz

• 6 kHz

• 12 kHz

An ultrasound scanner produces waves of frequency 2.5 MHz and speed 1500 ms^-1. What is the wavelength?

• 6 x 10^-4 m

• 0.0017 m

• 600 m

• 1.7 m

The curvature of waves is -0.4 D before a lens and 0.8 D after the same lens. What is the focal length of the lens?

• 0.4 m

• 1.2 m

• 0.83 m

• 2.5 m

Information is transferred at a rate of 2 Mbyte s^–1.

Calculate the time taken to transfer 6 Gbits at this rate to the correct s.f.

• 375 s

• 3000 s

• 0.3 s

• 400 s

Light from an unpolarised light source is passed through a polarising filter. The filter is rotated by 180 degrees. What happens.

• The brightness reduces.

• The brightness increases.

• The brightness stays the same.

• The light goes out.

The lens equations states that...

• Lenses add curvature to wavefronts.

• Lenses make the light brighter.

• Lenses are always round.

• Lenses always focus an image.

What is the wavelength of red light?

• 1000 nm

• 650 nm

• 450 nm

• 200 nm

A focused image of a distant object is formed 3.5 m away from a lens. What is the focal length of the lens?

• 0.29 m

• 3.5 m

• 7 m

• 3.5 mm