Intermediate 2 Waves & Optics Past Paper questions

Transcription

1 Intermediate 2 Waves & Optics Past Paper questions

2 2000 Q29. A converging lens has a focal length of 30 mm. (a) Calculate the power of this lens. (i) In the diagram below, which is drawn to scale, an object is shown at a distance of 80 mm from a lens. (c) The points marked F are one focal length from the lens. Copy the diagram onto squared paper and draw in two rays to show the formation of the image of this object. (ii) State two ways in which this image is different from the object. This lens is now fitted to a camera. The diagram below shows rays of light coming to the lens from a distant object. How far should the film be from the lens to give a sharp image? Explain your answer.

3 2001 Q28. A telecommunications company uses microwaves to transmit information between two positions A and B separated by a range of hills. A relay station on top of the hills receives and transmits the signals using curved reflectors. (a) Explain why a curved reflector is used to receive a signal. Your answer should include a diagram. The microwaves have a wavelength of 15 mm and a speed of 3x10 8 m/s in air. Calculate the frequency of the microwaves. (c) Calculate the minimum time taken by the microwaves to travel from A to B. (d) The relay station requires an energy source but is too remote to have a mains electricity supply. Suggest a possible alternative supply Q29. (a) The diagram shows the path of one ray of light from the top of an object placed in front of a converging lens. (i) Copy and complete the diagram to find the position of the image. Draw the image on your diagram. You may use the graph paper provided. (ii) Using information from the diagram, calculate the power of the lens. People with long sight need converging lenses to improve their vision. What is meant by long sight?

4 2002 Q28. A buzzer is placed in front of the open end of a tube. The tube is closed at the other end. A sound sensor linked to a computer is placed at the open end of the tube as shown. The buzzer produces a short pulse of sound. At the instant the buzzer is operated the computer starts to record the output voltage Vo of the sound sensor. The following graph of Vo against time is displayed on the computer screen. (a) (c) (d) Explain why the amplitude of the reflected sound is less than the amplitude of the incident sound. State the time between the first peak of the incident sound and the first peak of the reflected sound arriving at the sound sensor. The speed of sound in air is 340 m/s. Calculate the length of the tube. The frequency of the pulse is 1250 Hz. Calculate the wavelength of the pulse Q28. Typical wavelengths in air of light of different colours are given in the table below. (a) What is the speed of light in air? The frequency of a certain colour of light is 4.6x10 14 Hz. What colour is this light? You must justify your answer by calculation.

5 2002 Q29. Rays of light enter glass prisms as shown in diagrams 1 and 2. The critical angle for glass is 42º. (a) Complete diagram 1 to show the path of the ray after it strikes point P Complete diagram 2 to show the path of the ray after it strikes point Q Q28. (a) A ray of red light is incident on a glass block as shown below. (i) State the size of the angle of incidence. (ii) Complete the diagram to show the path of the ray inside the glass block.

6 In another experiment, rays of red light are incident on three semi-circular blocks of glass as shown. Each block is made of a different type of glass. The critical angle for each block of glass is given below. (c) From which block(s) does a ray of light refract through the straight edge? Explain your answer. One particular short sighted person requires a lens with a focal length of 200 mm. Six lenses, each of different type and power, are available. (i) Name the type of lens used to correct for short sight. (ii) From the lenses shown, choose the one that corrects for the short sight of the above person. You must Justify your answer by calculation.

7 2003 Q29. A satellite orbiting the earth has large panels as shown. The panels absorb light energy from the sun and changes it to electrical energy. (a) (i) Name a device which can change light energy to electrical energy. (ii) The panels produce a current of 4.5 A for 5 minutes. Calculate the charge moved in this time. The satellite uses electrical energy to generate microwaves which are transmitted to a receiving station on earth. (c) Explain how the curved reflector on the satellite aids the transmission of the microwaves. You must sketch a diagram as part of your answer. Microwaves are part of the electromagnetic spectrum. The diagram below shows the electromagnetic spectrum arranged in order of wavelength. Two parts of the spectrum, P and Q, have been omitted. Name the radiations P and Q. (d) All radiations in the electromagnetic spectrum travel at a speed of 3x10 8 m/s in space. The satellite transmits microwaves on the following three frequencies. 1.0x10 10 Hz, 9.0x10 9 Hz, 8.0x10 9 Hz Calculate the wavelength of the microwaves with the longest wavelength.

8 2004 Q28. Radio waves are transmitted between New York and Edinburgh. The ionosphere is a layer of charged particles above the Earth. Radio waves with frequencies below 40 MHz are reflected by the ionosphere. Radio waves with frequencies above 40 MHz pass through the ionosphere. (a) What is transferred by a radio wave? An aerial in New York transmits and receives signals of the following frequencies. 300 khz 3 MHz 30 MHz 300 MHz Which of these frequencies could be used for communication with Edinburgh by satellite? You must give a reason for your answer. (c) A satellite is km from both transmitting, and receiving stations in New York and Edinburgh. Calculate the minimum time for a signal to pass from York to Edinburgh using the satellite.

9 2004 Q29. (a) An optician wishes to attach labels to spectacles to show the power of their lenses. The following labels are available. One pair of spectacles has two lenses of the same power. The optician uses one of the lenses to obtain a sharp image of a distant window on a piece of paper as shown below. (i) Name this type of lens. (ii) Which label should be attached to these spectacles? You must show clearly the working which leads to your answer. The diagram below shows a ray of light incident on a glass surface. Complete the diagram to show the normal and the refracted ray. On your diagram, label the angle of incidence i and the angle of refraction r.

10 2005 Q30. (a) An osprey sees a fish in a loch. The diagram shows the path of a light ray from the fish to the osprey. (i) State the size of the angle of incidence. (ii) State the size of the angle of refraction. A bird watcher is using a telescope to watch the osprey. The eyepiece of the telescope acts as a magnifying lens. (i) On the square paper provided, copy the diagram below. Complete your diagram to show the size and position of the image formed by the lens. (ii) The focal length of this lens is 50 mm. Calculate the power of this lens.

11 2006 Q28. A student uses a lens of focal length 200 mm to produce a bright, sharp image of a lamp filament on a piece of white card. The lamp filament is positioned at a distance of 300 mm from the lens. The student completes an accurate scale diagram of this experiment on the graph paper shown below. Points marked F are each one focal length from the lens. Point 2F is two focal lengths away. Two rays of light have been drawn in. The scale is shown. The piece of card and the image have not been shown. (a) By considering the scale diagram, answer the following questions. (i) What is the distance between the lens and the sharply focussed image on the card? (ii) How does the height of the image compare with the height of the object? (iii) State one other difference between the image and the object. The student now moves the object further away from the lens. In which direction must the card be moved to keep the image sharp? (c) Calculate the power of the lens used by the student.

12 (d) A film projector in a cinema has a lens which forms an image of the film on a large, distant screen. The distance between the lens and the film is adjusted to produce a sharp image. Describe the change which must be made to the distance between the lens and the film if the projector is moved to a smaller cinema where the screen is closer to the projector Q29. The sun is 1.5x10 11 m from the Earth. The sun emits all radiations in the electromagnetic spectrum. All these radiations travel through space at 3x10 8 m/s. (a) (c) What do all waves transfer? Calculate the time taken for sunlight to reach Earth. The diagram below shows the electromagnetic spectrum in order of increasing frequency. One part has been missed out. (i) Name the missing radiation. (ii) Name an ionising radiation from the spectrum. (iii) What is meant by ionisation?

13 2006 Q29. (a) A large industrial laser is used to cut metal sheets in a factory. For safety, the laser beam travels to the metal along hollow tubes with Jointed "elbows". There is a plane mirror inside each "elbow" joint. At one joint in the tube, the laser beam must change direction by 110º. (i) What is the angle of incidence of the laser beam at the mirror? (ii) What is the angle of reflection of the laser beam at the mirror? A student aims a laser beam at a triangular glass prism as shown. The beam changes direction at point X. (i) Name the optical effect which occurs at point X. (ii) Suggest a suitable value of the critical angle for the type of glass used for this prism. You must explain your answer.

14 2007 Q27. When the sun shines during a shower of rain, a rainbow can sometimes be seen. The diagram shows what happens to sunlight when it enters a raindrop. (a) (i) Name the wave effect that happens at point P. (ii) Name the wave effect that happens at point Q. (iii) Which colour of the rainbow has the longest wavelength? As a raindrop falls it reaches a steady speed. Using Newton's laws of motion, explain why it falls at a steady speed.

15 2007 Q28. (a) Two types of waveform are shown. (i) Which waveform represents a longitudinal wave? (ii) Which waveform represents a sound wave? A signal generator is connected to a loudspeaker which produces a sound wave of frequency 2 khz. (c) (i) Calculate the wavelength of the sound wave in air. (ii) The loudspeaker is placed a distance of 10.2 m from a wall. Calculate the time taken for the sound to return to the loudspeaker. The loudspeaker is now placed in a tank of carbon dioxide gas. The frequency remains at 2 khz. What effect does this have on the wavelength of the Sound? Explain your answer.

16 2008 Q26. A karaoke machine consists of a microphone, amplifier, loudspeaker, DVD player and screen. (a) What energy change takes place in the microphone? The amplifier processes the signal from the microphone. What effect does the amplifier have on the signal's (i) frequency? (ii) amplitude? (c) A singer produces a note of frequency 850 Hz. The speed of sound in air is 340 m/s. Calculate the wavelength of this note in air. (d) The DVD player contains a laser. Light from this laser enters a small glass prism as shown. The glass has a critical angle of 40º. (i) Explain what is meant by the term "critical angle". (ii) Complete the diagram to show the path of the ray after it strikes point P.

17 2008 Q29. A "bug viewer" has a plastic chamber with a lens in the lid. It is used to get a magnified view of small insects placed on the base of the chamber. (a) What type of lens should be used? The lens used has a focal length of 60 mm and the base of the chamber is 30 mm from the lens. Complete this diagram by adding rays to show where the image of the bug will be formed. Use the squared ruled paper provided (small squares side). (c) (d) How would the shape of this lens have to be altered to give it a longer focal length? Name the eye defect which this type of lens could correct.

18 2009 Q27. A student is short sighted. (a) (i) What does the term "short sighted" mean? (ii) What type of lens is required to correct this eve defect? (iii) The focal length of the lens needed to correct the student's short sight is 180 mm. Calculate the power of this lens. In the eye, refraction of light occurs at both the cornea and the lens. Some eye defects can be corrected using a laser. Light from the laser is used to change the shape of the cornea. (i) State what is meant by refraction of light. (ii) The laser emits light of wavelength 7x10-7 m. Calculate the frequency of the light. (c) Lasers can be used in optical fibres for medical purposes. (i) Complete the path of the laser light along the optical fibre. (ii) Name the effect when the laser light hits the inside surface of the fibre.

19 2010 Q28. A satellite sends microwaves to a ground station on Earth. (a) (c) The microwaves have a wavelength of 60 mm. (i) Calculate the frequency of the waves. (ii) Determine the period of the waves. The satellite sends radio waves along with the microwaves to the ground station. Will the radio waves be received by the ground station before, after or at the same time as the microwaves? Explain your answer. When the microwaves reach the ground station they are received by a curved reflector. Explain why a curved reflector is used. Your answer may include a diagram.