2024, Prova 2

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1. 

   QUESTION 1 (4 marks) A coil of wire with 100 turns and a radius of 1.4 cm is placed perpendicular to a magnetic field of strength 0.510 T. The magnetic field strength is then changed to 0.030 T in 0.020 s. Calculate the magnitude of electromotive force (emf) induced in the coil. Show your working. Magnitude of emf = V

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2. 

   QUESTION 2 (6 marks) In a distant solar system, a star, planet and spaceship are aligned as shown. Not to scale Star mass = 1.9 × 1030 kg 2.4 × 1011 m 3.6 × 1011 m Planet Spaceship a) Calculate the strength of the star’s gravitational field experienced by the spaceship. Show your working. [3 marks] Gravitational field strength = m s–2 b) An observer on the planet measures the spaceship to be travelling directly towards the star at a speed of 1.9 × 108 m s–1. Calculate the distance between the spaceship and the star from the perspective of an astronaut on the spaceship. Show your working. [3 marks] Distance = m

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3. 

   QUESTION 3 (8 marks) A student conducted an experiment to address the following research question: What is the relationship between the angle of inclination and the acceleration from rest down a 2.4 m slope of a 0.050 kg object? θ Not to scale Data from the experiment was processed to produce the following graph. sin θ Acceleration down the slope (m s−2 ) 0.00 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 a) Determine the magnitude of the frictional force acting on the object when the angle of inclination is 45°. Use the graph and show your working. [5 marks] Magnitude of frictional force = N b) Calculate the final velocity of the object when the angle of inclination is 45°. Show your working. [3 marks] Final velocity = m s–1

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4. 

   QUESTION 4 (4 marks) Explain how a satellite can be accelerating yet maintain a constant speed in a circular orbit around a planet.

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5. 

   QUESTION 5 (3 marks) Explain the significance of the threshold frequency when incident light with a range of frequencies shines on a metal.

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6. 

   QUESTION 6 (11 marks) A photoelectric experiment was set up with a variable voltage between the collector and emitter, a resistor and an ammeter. There was no current detected when the light was off. Emitter Collector Light source A − + The potential difference required to reduce the current to 0 A was measured for different wavelengths of light. Potential difference (V) −10.0 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 −9.0 −8.0 −7.0 −6.0 −5.0 −4.0 −3.0 −2.0 −1.0 0.0 1/λ (×107 m−1) a) Determine the potential difference required to reduce the current to 0 A when light with a wavelength of 125 nm is shone on the emitter. Show your working and refer to the graph. [2 marks] Potential difference = V b) Use the graph to determine the work function of the emitter in eV. Show your working. [6 marks] Work function = eV c) The experiment was changed so that the variable voltage was removed and the light, with a frequency above the threshold frequency, was shining on the emitter. Predict the effect of increasing intensity from the light source on the current in the circuit. Explain your reasoning. [3 marks]

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7. 

   QUESTION 7 (4 marks) a) Contrast baryons and mesons in terms of composition. [2 marks] b) Contrast quarks and leptons in terms of the possible fundamental forces they experience. [2 marks]

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8. 

   QUESTION 8 (7 marks) A U-shaped magnet was placed on a digital scale. A current-carrying wire was connected to a variable power supply and passed through the space between the poles of the magnet. The length of wire within the magnetic field was 0.08 m, and the wire did not touch the magnet. Wire Digital scale 90° Magnet a) Sketch the magnetic field between the north and south poles of the magnet when there is no current in the wire. [1 mark] N N NS Wire

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