PHYSICS TEST 4 (TUESDAY)

In photo-emission, the number of photo-electrons ejected per second depends on the?

• frequency of the beam

• work function of the metal

• threshold frequency of the metal

• intensity of the beam

If electron are accelerated from rest through a potential difference of 10kv, what is the wavelength of the associated electron?

[m = 9.1 x 10^-31 kg, e = 1.6 x 10^-19 C, h = 6.6 x 10^-34 Js]

• 1.22 x 10^-11m

• 3.87 x 10^-10m

• 2.27 x 10¹¹m

• 2.27 x 10¹⁴m

The ground stated energy for the hydrogen atom is 5.44 x 10^-19. If an electron drops from zero energy to ground state, calculate the frequency of the emitted radiation?

[h = 6.6 x 10^-34 Js]

• 5.0 x 10¹⁶ Hz

• 2.0 x 10¹⁶ Hz

• 5.0 x 10¹⁵ Hz

• 2.0 x 10¹⁵ Hz

• No correct option

Which of the following statements is TRUE of photoelectric effect?

• it cannot occur in liquids

• the energy of the emitted electrons is independent of the work function of the surface

• the energy of the emitted electron depends on the wavelength of the incident light

• the greater the intensity of the incident light, the greater the energy of the emitted electron

Photometer is used to measure

• Kinetic energy of liberated electrons

• Intensity of light

• frequency of light

• wavelength of light

Calculate the energy of the third level of an atom if the ground state energy is -24.8 eV

• -9.20 eV

• -8.20 eV

• -2.75 eV

• -1.75 eV

A bar magnet is divided into two pieces, which of the following statement is correct?

• two new magnets are created

• the magnetic field of each separate piece becomes stronger

• the electric field is created

• the bar magnet is demagnetized

A magnet relay is a device used for?

• reading the magnitude of magnetic flux

• controlling another circuit carrying larger current

• turning in sports

• storing magnetic field

The device for measuring the angle of dip is 

• Dip circle

• Dip inclination

• Dip variation

• Dip meter

A closed coil of wire is placed near a magnet. The magnet lies along the axis of the coil. Under which of the following conditions would there be no current in the coil?

• When the coil is moved towards the stationary magnet

• When the coil is moved away from the stationary magnet

• When the coil is held stationary but the magnet is moved towards the coil

• When both the coil and magnet are held stationary

• When the coil is held stationary but the magnet is moved away from the coil