(i) Reduce/ prevent collisions of electrons with air molecules and hence increase current
(ii) Control/ limit current, lowers current
(iii) The energy of the radiation must be greater than the work function of the emitting surface.
(iv) Current flows when uv falls on the cathode; interruption of the uv beam cuts off the circuit: use with relay to switch on a second circuit with alarm.
Wilfykil answered the question on March 27, 2019 at 09:08
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Light of frequency 5.5x 1014 HZ is made to strike a surface whose work function is 2.5ev. Show that photoelectric effect will not take place....
(Solved)
Light of frequency 5.5x 1014 HZ is made to strike a surface whose work function is 2.5ev. Show that photoelectric effect will not take place. H= 6.6 X 1034Js
Date posted:
March 27, 2019
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Answers (1)
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State the purpose of cooling fins in the X-ray tube.
(Solved)
State the purpose of cooling fins in the X-ray tube.
Date posted:
March 27, 2019
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Answers (1)
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Explain why X-rays are appropriate in study of the crystalline structure materials.
(Solved)
Explain why X-rays are appropriate in study of the crystalline structure materials.
Date posted:
March 27, 2019
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Answers (1)
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An accelerating potential of 20kv is applied to an X-ray tube.
(Solved)
An accelerating potential of 20kv is applied to an X-ray tube.
i) What is the velocity with which the electron strikes the target?
ii) State the energy changes that take place at the target.
Date posted:
March 27, 2019
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Answers (1)
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For a given source of X-rays, how would the following be controlled.
(Solved)
For a given source of X-rays, how would the following be controlled.
i) Intensity
ii) The penetrating power
iii) The exposure to patients
Date posted:
March 27, 2019
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Answers (1)
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A photon has an energy of 5x10-19J. Calculate the wavelength associated with this photon.
(Solved)
A photon has an energy of 5x10-19J. Calculate the wavelength associated with this photon.
Date posted:
March 27, 2019
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Answers (1)
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How does the energy of ultra violet light compare to that of yellow light given that the energy E of a wave frequency f, is...
(Solved)
How does the energy of ultra violet light compare to that of yellow light given that the energy E of a wave frequency f, is given by E = hf, where h is plank’s constant?
Date posted:
March 27, 2019
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Answers (1)
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Distinguish between a photon and a quantum.
(Solved)
Distinguish between a photon and a quantum.
Date posted:
March 27, 2019
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Answers (1)
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State where Gamma rays originate.
(Solved)
State where Gamma rays originate.
Date posted:
March 27, 2019
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Answers (1)
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State the origin of all electromagnetic-radiation from radio waves to x-rays
(Solved)
State the origin of all electromagnetic-radiation from radio waves to x-rays
Date posted:
March 27, 2019
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Answers (1)
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Name two properties of ultraviolet radiation.
(Solved)
Name two properties of ultraviolet radiation.
Date posted:
March 27, 2019
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Answers (1)
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State 3 uses of infrared radiation.
(Solved)
State 3 uses of infrared radiation.
Date posted:
March 27, 2019
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Answers (1)
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Name two types of electromagnetic radiations whose frequencies are greater than that of visible light.
(Solved)
Name two types of electromagnetic radiations whose frequencies are greater than that of visible light.
Date posted:
March 27, 2019
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Answers (1)
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Arrange the following radiations in order of increasing wavelengths.
(Solved)
Arrange the following radiations in order of increasing wavelengths.
Ultraviolet, Gamma Rays, Radio Waves, Infra Red
Date posted:
March 27, 2019
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Answers (1)
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State one-way of detecting ultra violet radiation
(Solved)
State one-way of detecting ultra violet radiation
Date posted:
March 27, 2019
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Answers (1)
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A uniform plank of wood is pivoted at its centre. A block of wood of mass 2kg is balanced by a mass of 1.5 placed...
(Solved)
A uniform plank of wood is pivoted at its centre. A block of wood of mass 2kg is balanced by a mass of 1.5 placed 30cm from the pivot as shown.
i) Calculate the distance X
ii) When the same block of wood is partially immersed in water, the 1.5kg mass need to be placed at 20cm from the pivot to balance it. Calculate the weight of the water displaced.
Date posted:
March 27, 2019
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Answers (1)
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A right angled solid of dimensions 0.02m by 0.02m by 0.2m and density 2,700kg/m3 is supported inside kerosene of density 800kg/m3 by a thread which...
(Solved)
A right angled solid of dimensions 0.02m by 0.02m by 0.2m and density 2,700kg/m3 is supported inside kerosene of density 800kg/m3 by a thread which is attached to a spring balance. The long side is vertical and the upper surface is 0.1m below the surface of the kerosene.
i) Calculate the force due to the liquid on the lower upper surface of the solid.
ii) Calculate the up thrust and determine the reading on the spring balance.
Date posted:
March 27, 2019
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Answers (1)
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The figure below shows a cube of a certain wood whose density is the same as that of water. The cube is held on the...
(Solved)
The figure below shows a cube of a certain wood whose density is the same as that of water. The cube is held on the surface of the water in a long cylinder. Explain what happens to the cube after it is released
Date posted:
March 27, 2019
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Answers (1)
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A mass of 120 g half immersed in water displaced a volume of 20 cm3. Calculate the density of the object
(Solved)
A mass of 120 g half immersed in water displaced a volume of 20 cm3. Calculate the density of the object
Date posted:
March 27, 2019
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Answers (1)
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Determine the density of glass that weighs 0.5N in air and 0.3N in water.
(Solved)
Determine the density of glass that weighs 0.5N in air and 0.3N in water.
Date posted:
March 27, 2019
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Answers (1)