Physics Paper 1 Mistakes Flashcards
What does the gradient of a speed-time graph represent
Acceleration
What does the area under a speed-time graph represent
DIstance
Explain how the emission of light from the fluorescent screen shows that the electrons incident on it are behaving as particles
Electrons must provide enough kinetic energy instantly to cause the excitation.
The atom/energy transfer in a 1 to 1 interaction.
Light emission due to excitation and de-excitation of electron.
Photon emitted when atoms de-excite or electrons move to lower energy levels
Suggest two features of the design that ensure that there is no deviation (refraction) of the ray as it leaves the first prism and enters the windscreen glass
- Prism material has the same optical density as the windscreen.
- Prism is fitted to windscreen without gaps
White light is incident on a single slit. After leaving the slit, the diffracted light passes through a green filter to reach the screen.
Describe the pattern produced on the screen
Bright green central fringe and susbsidiary maxima of decreasing intensity.
Central maxima is twice the width of other maxima.
White light is incident on a single slit. After leaving the slit, the diffracted light passes through a green filter to reach the screen.
The green filter is replaced with a red filter. Describe the change in the pattern produced on the screen.
Wider central maxima.
Subsequent maxima further apart
Explain why the reading on the voltmeter decreases as the brightness of the lamp increases
Increase in current.
Increase in lost volts
What happens to a graph showing variation of amplitude with frequency when there is increased damping
Max amplitude decreases.
Peak shifts to the left
A student suggests that the K0 and anti kaon k-0 are the same particle.
Discuss whether this suggestion is correct.
Kaon is down quark, anti strange quark
Antikaon is anti down quark, strange quark
Therefore not the same
A current is measured on the microammeter only when EM radiation with a frequency greater than a certain value is incident on the photoemissive surface.
Explain why the current reaches a constant value for positive values of V
The number of photoelectrons emitted per second depends on the intensity.
Constant current is reached when all photoelectrons released, reach the anode.
A current is measured on the microammeter only when EM radiation with a frequency greater than a certain value is incident on the photoemissive surface.
Explain why current decreases as the value of V becomes more negative
Photoelectrons are released with a range of KE.
When V is negative, photoelectrons lose KE crossing to the anode.
As the V is increasingly negative, fewer of the photoelectrons have sufficient KE to cross to anode.
A student investigates the interference of sound wave using two loudspeakers, P and Q, connected to a signal generator. Each loudspeaker acts as a point source of sound.
Explain why the two loudspeakers are coherent sources of sound waves
The phase difference is constant and the sound waves have the same wavelength.
This is achieved by both speakers being connected to the same signal generator
Discuss one advantage and one difficulty when using superconductors in electrical transmission over long distances
Advantage - Zero resistance and so less power loss in cables.
Difficulty : Must be kept below the critical temperature at all times and it is difficult to maintain this temperature as it is so low
The microwaves from the transmitted T are vertically polarised and have a wavelength of 3cm.
The microwaves are detected at the receiver by a vertical metal rod R.
Explain how the apparatus can be used to demonstrate that the waves from T are vertically polarised.
- Rotate aerial in vertical plane.
- When aerial vertical, signal is MAX and when horizontal, the signal is MIN
- Max occurs when aerial is aligned with plane of polarisation of microwave
When can Youngs double slit equation be used to determine the wavelength
When the slit separation is much smaller than the distance from the slits to the screen
