Answer question

14 7 (a) A student investigates the potential difference across a light emitting diode (LED). The student records the wavelength .1. of the light emitted from the LED from a datasheet. The student measures the minimum potential difference V across the LED when the LED rst starts to emit light. The student then repeats the experiment for LEDs with different values of A. For each value of A. the student measures Vand determines the absolute uncertainty in V. The student plots a graph of potential difference V (y-axis) against 1M (Jr-axis) including the error bars in V and a straight line of best t. 2.5 WV 2.4 2.3 2.2 2.1 2.0 1.6 1.7 1.8 1.9 2.0 2.1 2.2 900R2021 1 5 It is suggested that the relationship between Vand 2. is V=?:+D where h is the Planck constant, c is the speed of light in a vacuum. a is the elementary charge and D is a constant. 16 (b) In a different experiment, photoelectrons are emitted from the surface of an aluminium plate when electromagnetic radiation of wavelength 98 nm falls on the plate. The work function of aluminium is 4.1 eV. (i) Calculate the maximum kinetic energy KEmax in joules (J) of the photoelectrons emitted from the surface of the aluminium