Category: A-level modern physics

Outline the experimental evidences for the quantum theory of matter.

09/05/2021 2

Outline the experimental evidences for the quantum theory of matter. The quantum theory of matter states that energy of a radiation exists in discrete packets ... Read More

What is  Nuclear fusion?

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What is  Nuclear fusion? Nuclear fusion is the combination of light nuclei to form a heavier nucleus accompanied by release of energy. Please Subscribe to ... Read More

What is nuclear fission?

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What is nuclear fission? Nuclear fission is the splitting of heavy unstable nucleus into two nuclei accompanied by release of energy. Please Subscribe to promote ... Read More

Describe an experiment to verify Einstein’s equation for the photoelectric effect and explain how Plank’s constant may be obtained from the experiment.

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Describe an experiment to verify Einstein’s equation for the photoelectric effect and explain how Plank’s constant may be obtained from the experiment. A radiation of ... Read More

Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by increasing the high tension potential difference across the tube 

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Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by increasing the high tension potential difference across the tube  Penetrating ... Read More

Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by changing the filament current 

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Explain how intensity and penetrating power of X-rays from X-ray tube would be affected by changing the filament current  When the filament current is increased, ... Read More

Sketch the current –voltage characteristic of the Geiger- Muller tube and explain its main features.

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Sketch the current –voltage characteristic of the Geiger- Muller tube and explain its main features.  OA – the operating voltage is not enough to attract ... Read More

What are radioisotopes? 

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What are radioisotopes?  Radioisotope are radioactive atoms of the same element having the same atomic number but different atomic mass Please Subscribe to promote this ... Read More

State two disadvantages of discharge tubes when used to study cathode rays. 

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State two disadvantages of discharge tubes when used to study cathode rays.  A gas is needed at very low pressure which may not be easy ... Read More

Describe an experiment to measure the ratio of the charge to mass of an electron

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Describe an experiment to measure the ratio of the charge to mass of an electron The electrons are produced thermionically by a hot filament cathode ... Read More

Explain, using suitable sketch graph, how X-ray spectrum in an X-ray tube are formed. 

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Explain, using suitable sketch graph, how X-ray spectrum in an X-ray tube are formed.  The spectrum consists of two major components, i.e. the continuous (background) ... Read More

Explain the purpose of Argon gas at low pressure of the following in a Geiger-Muller tube

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Explain the purpose of Argon gas at low pressure of the following in a Geiger-Muller tube  Argon form ions when it is struck by ionizing ... Read More

 Explain the purpose of a thin mica window of the following in a Geiger-Muller tube

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 Explain the purpose of a thin mica window of the following in a Geiger-Muller tube    To allow easy entry of ionizing particles in the ... Read More

Draw a labelled circuit to show a triode being used as a single-stage voltage amplifier.

09/05/2021 0

Draw a labelled circuit to show a triode being used  as a single-stage voltage amplifier. Please Subscribe to promote this website. Subscription is free Share ... Read More

Sketch and describe the collector-current against collector-emitter voltage characteristic of a junction transistor.

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Sketch and describe the collector-current against collector-emitter voltage characteristic of a junction transistor. For small values of V, Ic increases linearly with V but strongly ... Read More

Describe the structure of a junction transistor.

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Describe the structure of a junction transistor. A transistor consist of 3 layers of P- and n- semiconductors called respectively emitter, base and collector. The ... Read More

Describe briefly the mechanism of thermionic emission.

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Describe briefly the mechanism of thermionic emission. High temperature raises the kinetic energy of free electrons in metallic lattice and make them to escape from ... Read More

Explain how line spectrum accounts for existence of discrete energy levels in an atom. 

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Explain how line spectrum accounts for existence of discrete energy levels in an atom. Atoms of a particular element emit radiation with definite frequencies or ... Read More

What is meant by a line spectrum?

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What is meant by a line spectrum? Line spectrum are discontinuous lines produced by electronic transitions within the atom as the electrons fall back to ... Read More

Distinguish between excitation and ionization energies of an atom

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Distinguish between excitation and ionization energies of an atom. Excitation energy is the energy required to remove an electron from an atom in its ground ... Read More

Explain the observations made in the Rutherford α-particle scattering experiment.

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Explain the observations made in the Rutherford α-particle scattering experiment. Most alpha particle passed through metal foil undeflected. This is because most space in an ... Read More

Distinguish between continuous and line spectra in an X-ray tube. 

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Distinguish between continuous and line spectra in an X-ray tube.    Continuous spectrum is produced by multiple collision of electrons with target atoms.   Line ... Read More

With the aid of a well labelled diagram, describe how stopping potential of a metal can be measured.

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With the aid of a well labelled diagram, describe how stopping potential of a metal can be measured. An evacuated electric cell X that has ... Read More

Describe with the aid of a well labelled diagram, the structure and mode of operation of a C.R.O 

09/04/2021 0

Describe with the aid of a well labelled diagram, the structure and mode of operation of a C.R.O The cathode ray oscilloscope consists of cathode ... Read More

Derive an expression for the amplification factor, µ, in terms of anode resistance, Ra and mutual conductance, gm, for a triode valve. 

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Derive an expression for the amplification factor, µ, in terms of anode resistance, Ra and mutual conductance, gm, for a triode valve. Please Subscribe to ... Read More

With the aid of a labelled diagram explain full wave rectification.

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With the aid of a labelled diagram explain full wave rectification. Four diodes are arranged in a bridge network as shown above. If A s ... Read More

Define the terms Mutual conductance as applied to a triode

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Define the terms Mutual conductance as applied to a triode   Mutual conductance is the ratio of change in anode current to change in grid ... Read More

Define the terms amplification factor as applied to a triode

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Define the terms amplification factor as applied to a triode Amplification factor is the ratio of change in anode voltage to change in grid voltage ... Read More

Define the term space charge as applied to a triode

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Define the term space charge as applied to a triode Space charge is the cloud of electrons formed around the cathode when the p.d across ... Read More

Explain the term avalanche as applied to an ionization chamber. 

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Explain the term avalanche as applied to an ionization chamber. A n avalanche is a large number of moving ionized particle created as a result ... Read More

With the aid of a diagram, describe an experiment to show that cathode rays travel in straight line

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With the aid of a diagram, describe an experiment to show that cathode rays travel in straight line Electrons emitted from the cathode, C are ... Read More

What is a decay constant?

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What is a decay constant? Decay constant is the fractional number of disintegrations per second. Please Subscribe to promote this website. Subscription is free Share ... Read More

Draw anode current-diode voltage curves of a thermionic diode for two different filament currents and explain their main features. 

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Draw anode current-diode voltage curves of a thermionic diode for two different filament currents and explain their main features. The current increases with the positive ... Read More

Define space charge as applied to thermionic diodes.

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Define space charge as applied to thermionic diodes. Space charge is cloud of negative charge around the cathode at low anode potential difference.   Please ... Read More

Explain the physical processes in an X-ray tube that account for characteristic lines 

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Explain the physical processes in an X-ray tube that account for characteristic lines At high tube voltages, the bombarding electron penetrate deep into the atom ... Read More

Explain the physical processes in an X-ray tube that account for cut off wavelength 

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Explain the physical processes in an X-ray tube that account for cut off wavelength Electrons from the cathode strike the target and lose all their ... Read More

Draw a graph to illustrate the variation of ionization current and p.d across an ionization chamber and explain its features. 

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Draw a graph to illustrate the variation of ionization current and p.d across an ionization chamber and explain its features. Region OA: Current detected increases ... Read More

Describe an experiment to demonstrate photo electric effect.

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Describe an experiment to demonstrate photo electric effect. Freshly cleaned zinc plate is placed on top of a negatively charged electroscope. Ultraviolet radiation is directed ... Read More

With the aid of a labelled diagram, describe how cathode rays are produced.

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With the aid of a labelled diagram, describe how cathode rays are produced. Hot Cathode C produces electrons by thermionic emission. The electrons are accelerated ... Read More

Explain how Bohr’s model of the atom addresses the two main failures of Rutherford’s model. 

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Explain how Bohr’s model of the atom addresses the two main failures of Rutherford’s model. Orbiting electrons experience centripetal acceleration. Therefore they continuously emit electromagnetic ... Read More

State Rutherford’s model of the atom. 

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State Rutherford’s model of the atom. The positive charge of an atom and nearly all the mass is concentrated in a small volume at the ... Read More

Explain how the half-life of a short lived radioactive source can be obtained by use of a Geiger-Muller tube. 

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Explain how the half-life of a short lived radioactive source can be obtained by use of a Geiger-Muller tube. Switch on the GM-tube, note and ... Read More

With the aid of a labelled diagram, describe the operation of a Geiger-Muller (GM) tube 

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With the aid of a labelled diagram, describe the operation of a Geiger-Muller (GM) tube The thin mica window allows the passage and detection of ... Read More

With reference to a Geiger-Muller tube, define the back ground count rate

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With reference to a Geiger-Muller tube, define the back ground count rate It is the activity detected by the GM tube in absence of the ... Read More

With reference to a Geiger-Muller tube, define the  a quenching agent. 

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With reference to a Geiger-Muller tube, define the  a quenching agent.  It is a halogen gas placed in a Geiger-Muller tube to prevent positive ions ... Read More

State Bragg’s law of X-ray diffraction 

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State Bragg’s law of X-ray diffraction It states that for constructive interference of diffracted X-rays to occur, the path difference s an integral multiple of ... Read More

State the laws of photoelectric emission

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State the laws of photoelectric emission The time lag between irradiation of the metal surface and emission of the electrons by the metal surface is ... Read More

Define  Faraday’s constant. 

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Define  Faraday’s constant. Faradays constant is the charge required to liberate one mole of monovalent ions during electrolysis.   Please Subscribe to promote this website. ... Read More

Define Avogadro’s constant.

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Define Avogadro’s constant. Avogadro’s constant is the number of atoms in one mole of substance.   Please Subscribe to promote this website. Subscription is free ... Read More

Explain the motion of an electron projected perpendicularly into a uniform magnetic field.

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Explain the motion of an electron projected perpendicularly into a uniform magnetic field. By Fleming’s left hand rule, the electrons experience a force which is ... Read More

Draw a sketch graph showing the variation of time base voltage with time 

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Draw a sketch graph showing the variation of time base voltage with time Please Subscribe to promote this website. Subscription is free Share with a ... Read More

What is time base as applied to a Cathode Ray Oscilloscope? 

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What is time base as applied to a Cathode Ray Oscilloscope? Is a circuit connected to the x-plate of cathode ray oscilloscope to sweep the ... Read More

Describe how positive rays are produced. 

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Describe how positive rays are produced. Positive rays are produced when a stream of electrons is passed through a vapor (gas) in discharge tube. The ... Read More

With the aid of a labelled diagram, describe the operation of a diffusion type cloud chamber. 

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With the aid of a labelled diagram, describe the operation of a diffusion type cloud chamber. The base of the chamber is maintained at low ... Read More

An electron of mass m and charge –e, is considered to move in circular orbit about a proton. Write down the expression for the electric force on the electron. 

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An electron of mass m and charge –e, is considered to move in circular orbit about a proton. Write down the expression for the electric ... Read More

State Bohr’s postulates of an atom 

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State Bohr’s postulates of an atom Bohr’s model state that electrons move in allowed orbits round the nucleus and while in orbits, they do not ... Read More

Explain briefly diffraction of X-rays by crystals and derive Bragg’s law. 

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Explain briefly diffraction of X-rays by crystals and derive Bragg’s law. A parallel beam of monochromatic X-rays incident on a crystal is reflected from successive ... Read More

What is mass defect?

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What is mass defect? Mass defect s the difference between the mass of nucleons that make up a nucleus and the mass of a nucleus. ... Read More

State the energy changes that take place in the production of X-rays in an X-ray tube. 

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State the energy changes that take place in the production of X-rays in an X-ray tube. Electrical energy → kinetic energy → X-rays + heat ... Read More