Fourth Form Quiz

X-rays are used to image broken bones because...

• Bones absorb X-rays while X-rays are transmitted through soft tissue.

• Soft tissues absorb X-rays while X-rays are transmitted through bone.

• X-rays have a relatively high frequency and they turn photographic film black.

• X-rays are not harmful and so ideal for medical imaging.

Radio-waves are used for long-range communication because....

• They have a relatively long wavelength which means they are less susceptible interference.

• They reflect off the the upper-atmosphere (ionosphere) making them ideal for long range communication.

• They travel at the speed of light and this speeds up communication.

• They have a short range of wavelengths making it easier to encode information in them.

Microwaves are used for satellite communication because...

• They have a very high frequency and are therefore able to transmit information at a much faster rate.

• They are relatively long wavelength and so less susceptible to interference.

• They are relatively long wavelength and travel at the speed of light.

• They can penetrate the Earth's upper atmosphere (ionosphere)

Gamma rays are used to sterilize medical equipment because...

• They have a low frequency and so less likely to cause damage to the equipment.

• They have a very high frequency and able to destroy bacterial cells and viruses.

• They cause metal instruments to heat up thereby sterilizing the metal surfaces.

• They are relatively straightforward to produce.

Ultraviolet light is used for detecting forgeries because...

• It is invisible to the human eye.

• It causes certain inks to fluoresce and produce visible light when UV is shone upon them.

• UV is not harmful to humans.

• UV (or so called black light) has lower frequency than microwaves and so less likely to cause damage to any artifact being examined.

Which of these is not a vector?

• Weight

• Upthrust

• Speed

• Velocity

• Acceleration

Which of these is not a scalar?

• Mass

• Temperature

• Density

• Light intensity

• Upthrust

Which of these is the correct definition for a vector?

• A physical quantity that have magnitude and direction

• A physical quantity that has only magnitude

Which of the following statements about electromagnetic waves is correct?

• they all have the same amplitude

• they all have the same frequency

• they all have the same speed in free space

• they all have the same wavelength

A buzzer produces a sound wave of frequency 2.9 kHz and wavelength 12 cm

• 2508 m/s

• 240 m/s

• 35 m/s

• 348 m/s