Unit 1 Flashcards
State and explain one reason why it is an advantage for a rechargeable battery to have a low internal resistance. (2 marks)
- Charges quicker
- Because less energy is wasted.
Pair production can occur when a photon interacts with matter. Explain the process of pair production. (2 marks)
- Photon interacts with atom
- It’s energy is used to create a particle/antiparticle pair.
Explain why emitted electrons (photo-electric effect) have a range of kinetic energies up to a maximum value. (3 marks)
- Energy given to electron is fixed.
- Energy required for electron to be emitted.
- Deeper electrons require energy to get to the surface.
State and explain the effect on emitted electrons of decreasing the frequency of incident radiation while keeping the intensity constant. (2 marks)
- MAXIMUM kinetic energy of emitted electrons decreases.
- provided that the frequency remains above threshold.
An oscilloscope has a screen of eight vertical and ten horizontal divisions. Describe how you would use the oscilloscope to display an alternating waveform (3 marks)
- Connect to the y input.
- Change the time base if needed.
- Alter y gain if needed.
Components are in series. State and explain what would happen to the reading on the voltmeter if the intensity of the light incident on the 50kohm LDR increases. (in series with 5kohm R and 35kohm variable resistor) (2 marks)
- light intensity increases so resistance decreases.
- more share of voltage, so reading decreases.
Explain how the lack of a time delay was used as experimental evidence to develop the particle model for light? (2 marks)
- Light travels as a particle
- 1 to 1 interaction
State and explain the effect on the voltmeter reading of the internal resistance of the battery in the circuit was not negligible. (2 marks)
- terminal dp now lower (cell pd)
- hence dp across resistor will decrease
Where does the electron come from on the left hand side of the electron capture equation? (1 mark)
Inner shell of atom
State what is meant by the ionisation energy of hydrogen. (2 marks)
- energy required to remove and electron
- from ground state
Oscilloscope. Time base off, connected to y input. ac voltage. Explain why a vertical line is now on the screen. (2 marks)
- the voltage changes direction
- this makes the spot move up and down
Describe the process by which mercury atoms become excited in a fluorescent tube. (3 marks)
- electrons flow through tube
- and collide with mercury atoms
- raising the electrons of the mercury atoms to a higher energy level.
State and explain why a filament lamp is most likely to fail as it is switched on. (2 marks)
- Initially a larger current
- there is a sudden rapid change in temperature which reduces the current as resistance increases with temperature.
Pair production. Describe what is likely to happen to the positron shortly after it is created. (2 marks)
- Annihilated
- Converting mass into energy of two or more photons.
An electron is incident on a hydrogen atom. Explain why the electron in the ground state becomes excited to n=2. (2 marks)
- electron gives atom excess energy.
- EXACT energy to move to n=2
