OCR GCE AS Level Physics A Paper 2 June 2016 question paper H156/02

Describe the difference between longitudinal and transverse waves.

A loudspeaker emits a sound wave. A microphone is connected to an oscilloscope. The trace produced on the screen of the oscilloscope due to the sound wave is shown in Fig. 1.

The vertical y-sensitivity of the oscilloscope is set to 10 mV div⁻¹ and the horizontal time-base is set to 0.50 ms div⁻¹.

Determine the amplitude of the signal displayed on the oscilloscope.

The frequency f of the sound wave is the same as the frequency of the signal shown in Fig. 1. Determine f.

The speed of sound in air is 330 m s⁻¹. Calculate the wavelength of the sound wave.

The output from the loudspeaker is adjusted so that the intensity of the sound wave at the microphone is a quarter of its original value. The controls on the oscilloscope are not altered.

Describe and explain how the signal displayed on the oscilloscope will be different from Fig. 1.

A student is investigating the interference of microwaves after passing through two narrow slits.

State the principle of superposition of waves.

For interference effects to be observed, the waves from the two slits must be coherent State what is meant by the term coherent.

A student sets up an experiment to demonstrate the interference of microwaves as shown in Fig. 2.

A microwave transmitter is placed in front of the two slits. A microwave detector is moved along the line PQ. Maxima are detected at points A, C, and E. Minima are detected at points B and D.

The distance travelled by the microwaves from each slit to point A is the same. State the path difference in terms of the wavelength of the microwaves from the two slits at

1 point C

2 point D

The separation between the slits is increased.

State and explain the effect this has on the separation between adjacent maxima.

In a hockey match a hockey ball is hit 18.0 m from the front of the goal. The ball leaves the hockey stick with initial velocity v at an angle to the horizontal ground. The ball passes over the goal at a maximum height of 2.0 m as shown in Fig. 3.

The initial vertical component of the velocity of the ball is 6.3 m s⁻¹. Air resistance has negligible effect on the motion of the ball.

Show that the time t taken for the ball to reach the maximum height is about 0.6 s.

Use the answer to (a)(i) and Fig. 3 to show that the horizontal component of the velocity of the ball as it leaves the hockey stick is about 30 m s⁻¹.

Calculate the magnitude of the initial velocity v of the ball.

v =........ m s⁻¹

The hockey ball has a mass of 0.160 kg.

Calculate the initial kinetic energy E_k of the ball as it leaves the hockey stick.

Calculate the change in gravitational potential energy E_p of the ball as it moves from the ground to the maximum height.

Calculate the kinetic energy of the ball at the maximum height.

The hockey ball is replaced with a ball that is affected by air resistance. This ball is hit with the hockey stick so that it leaves the stick with the same initial velocity v.

On Fig. 3 sketch the path the ball is likely to take.

A student is investigating a potential divider circuit containing a light-dependent resistor (LDR). The student sets up the circuit shown in Fig. 4.

The battery has an e.m.f. of 6.0 V and negligible internal resistance. The resistor has a resistance of 1.2 k. In a dark room the voltmeter reading is 5.1 V.

Show that the resistance R_LDR of the LDR is 6800 .

Calculate the current I delivered by the battery.

The circuit is moved so that the LDR is now in sunlight.

Without reference to the potential divider equation, describe and explain how the readings on the ammeter and voltmeter will change.

A student is investigating the resistance of a conducting putty.

The density of conducting putty is 5300 kg m⁻³. The student has a 100 g sample of this putty. Show that the volume V of the sample is about 1.9 × 10⁻⁵ m³.

The student rolls the putty into a cylinder shape and connects the ends of the cylinder to metal plates as shown in Fig. 5.1. The ohm-meter is used to measure the resistance R of the conducting putty.

Suggest why the student uses large metal plates at the ends of the conducting putty.

Describe how the student can check that the diameter of the conducting putty is constant.

The student measures the resistance R of the conducting putty for different length L. The volume of the conducting putty is kept constant.

The student’s results are shown in Table 5.2.

Complete the table for the missing value of L².

Each length is measured to the nearest millimetre using a ruler. Determine the percentage uncertainty in L² for L = 0.049 m.

Fig. 5.3 shows the graph of R (y-axis) against L² (x-axis).

Plot the missing data point and draw the straight line of best fit.

Determine the gradient of the line of best fit.

Fig. 5.3

The relationship between R and L is

where is the resistivity of the conducting putty and V is the volume.

Use your answer to (d)(ii) and V = 1.9 × 10⁻⁵ m³ to determine a value for . Include an appropriate unit.

* A student wishes to determine experimentally the breaking stress of a metal in the form of a thin wire.

Describe with the aid of a diagram how this experiment can be safely conducted, and how the data can be analysed to determine the breaking stress of the metal.

* A gold leaf electroscope is used to demonstrate the photoelectric effect. A zinc plate is placed on top of the electroscope. The zinc plate is negatively charged as shown in Fig. 7.

White light from a table lamp is allowed to fall on to the electroscope from a distance of 10.0 cm. The experiment is then repeated with light from a distance of 4.0 cm. Both experiments are then repeated with ultraviolet radiation. The electroscope is fully charged before each experiment.

The observations are recorded in Table 7.

Explain how these observations demonstrate the photoelectric effect and provide evidence

for the particulate nature of electromagnetic radiation.

In another experiment, electromagnetic radiation of frequency 9.60 × 10¹⁴ Hz falls on a negatively-charged metal surface with a work function of 3.2 eV.

Calculate the maximum kinetic energy E_{k (max)} in joules of the particles emitted from the surface of the metal.

Electron diffraction provides evidence for the wave-like behaviour of particles. Electrons are diffracted by a thin slice of graphite.

In one experiment, electrons are accelerated from rest through a potential difference of 300 V.

Show that the final speed v of the electrons is 1.0 × 10⁷ m s⁻¹.

Determine the de Broglie wavelength of the electrons.

After the electrons are diffracted by the graphite they hit a fluorescent screen. The electrons are diffracted because of the spacing between the carbon atoms is comparable with the de Broglie wavelength of the electrons. Fig. 8 shows the diffraction pattern (bright rings) seen on the fluorescent screen when the electrons are accelerated through a potential difference of 300 V.

The potential difference is now increased. Explain how the diffraction pattern will change.