(i) 2 x 2 = 4 milliseconds for one wave
T = $\frac{4}{1000}$ = 0.004 s
(ii) f = $\frac{1}{T}$ = $\frac{1}{0.004}$ = 250Hz
johnmulu answered the question on June 6, 2017 at 05:36
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Figure 9 shows a cathode ray tube in which a beam of electrons is cast on the screen.
(Solved)
Figure 9 shows a cathode ray tube in which a beam of electrons is cast on the screen.
(i) State how electrons are produced in the tube.
(ii) state how electron beam is detected.
(iii) State the reason for having a variable potential difference (p.d) at the: (I) grid (II) anodes
Date posted:
June 6, 2017
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Answers (1)
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Figure 10 shows the main features of a cathode ray oscilloscope (CRO).
(Solved)
Figure 10 shows the main features of a cathode ray oscilloscope (CRO).
(i) Name the part labeled M and N.
(ii) Explain how electrons are produced in the tube.
(iii) State why the tube is highly evacuated.
Date posted:
June 6, 2017
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Answers (1)
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Figure 14 (a) is a diagram of a cathode ray tube. M and N are parallel vertical plates.
(Solved)
Figure 14 (a) is a diagram of a cathode ray tube. M and N are parallel vertical plates.
When switch S is open, a spot is seen at the centre of the screen as shown in Figure 14
(i) State what happens to the sport when S is closed.
(ii) State what would happen to the spot if the potential difference across MN is increased
Date posted:
June 6, 2017
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Answers (1)
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Figure 14 shows the features of a cathode ray tube.
(Solved)
Figure 14 shows the features of a cathode ray tube.
(i) Name the parts labeled A and B.
(ii) Explain how the electrons are produced in the tube.
(iii) State two functions of the anodes.
(iv) At what part of the cathode ray tube would the time be connected?
(v) Why is a vacuum created in the tube?
Date posted:
June 5, 2017
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Answers (1)
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Figure 6 shows a tube for investing the properties of a beam of electrons. Use the information in the figure to answer the question.
(Solved)
Figure 6 shows a tube for investing the properties of a beam of electrons. Use the information in the figure to answer the question.
What property of the beam of electrons shows that the electrons are traveling at a very high speed?
Date posted:
June 5, 2017
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Answers (1)
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Figure 3 shows the main features of a cathode ray tube (CRT) of a cathode ray oscilloscope (CRO).
(Solved)
Figure 3 shows the main features of a cathode ray tube (CRT) of a cathode ray oscilloscope (CRO).
(i) Describe how the electrons are produced in the tube.
(ii) State and explain the function of the grid.
(iii) State what would be observed on the screen if an a.c voltage is connected across the y-plates.
Date posted:
June 5, 2017
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Answers (1)
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Figure 12 shows a section of a house wiring system.
(Solved)
Figure 12 shows a section of a house wiring system.
(i) Name:
the circuit labeled P.
the terminals labeled X and Y.
(ii) I. State the purpose of R in the circuit.
II. Give a reason why R is connected to Y but not to X.
(iii) Why is the earthing necessary in such a circuit?
Date posted:
June 5, 2017
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Answers (1)
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Figure 17 shows the electric wiring of an electric heater. A, B, C are the mains wires.
(Solved)
Figure 17 shows the electric wiring of an electric heater. A, B, C are the mains wires.
Identify A, B and C.
Date posted:
June 5, 2017
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Answers (1)
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Figure 4 shows a simple transformer connected to a 12 V a.c source and an a.c voltmeter.
(Solved)
Figure 4 shows a simple transformer connected to a 12 V a.c source and an a.c voltmeter.
By counting the number of turns in each coil, determine the reading on the voltmeter.
Date posted:
June 5, 2017
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Answers (1)
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Figure 15, shows two coils A and B placed close to each other. A is connected to a steady D.C. Supply and a switch, B is connected to a sensitive galvanometer.
(Solved)
Figure 15, shows two coils A and B placed close to each other. A is connected to a steady D.C. Supply and a switch, B is connected to a sensitive galvanometer.
(i) The switch is now closed. State the observations made on the galvanometer.
(ii) Explain what would be observed if the switch is then open.
Date posted:
June 5, 2017
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Answers (1)
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Figure 6 shows a horizontal conductor in a magnetic field parallel to the plane of the paper.
(Solved)
Figure 6 shows a horizontal conductor in a magnetic field parallel to the plane of the paper.
State the direction in which the wire may be moved so that the induced current is in the direction shown by the arrow.
Date posted:
June 5, 2017
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Answers (1)
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Figure 5 shows a magnet being moved towards a stationary solenoid. It is observed that a current flows through the circuit in a direction Q to P.
(Solved)
Figure 5 shows a magnet being moved towards a stationary solenoid. It is observed that a current flows through the circuit in a direction Q to P.
Explain: (i) How the current is produced
(ii) Why the current flows from Q to P.
Date posted:
June 5, 2017
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Answers (1)
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Figure 12 shows two circuits close to each other.
(Solved)
Figure 12 shows two circuits close to each other.
When the switch is closed, the galvanometer shows a reading and then returns to zero. When the switch is then opened, the galvanometer shows a reading in the opposite direction and then returns to zero. Explain these observations.
Date posted:
June 5, 2017
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Answers (1)
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Figure 13 shows a simple microphone in which sound waves from the person talking cause the cardboard diaphragm to vibrate.
(Solved)
Figure 13 shows a simple microphone in which sound waves from the person talking cause the cardboard diaphragm to vibrate.
(i) Explain how a varying current is induced in the coil when the diaphragm vibrates
(ii) State two ways in which the induced current in (i) above can be increased.
Date posted:
June 5, 2017
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Answers (1)
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Figure 10 shows a simple electric generator.
(Solved)
Figure 10 shows a simple electric generator.
Name the parts labeled P and Q
Date posted:
June 5, 2017
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Answers (1)
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In the set up in Figure 19, the magnet is moved towards the coil and stopped when inside the coil.
(Solved)
In the set up in Figure 19, the magnet is moved towards the coil and stopped when inside the coil.
It is observed that the galvanometer deflects to one side and then goes back to zero. Explain this observation.
Date posted:
June 5, 2017
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Answers (1)
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Figure 7 shows pendulum A and pendulum B freely suspended between the poles of identical magnets. Pendulum A is made of thick copper plate while B is made a copper plate with slots.
(Solved)
Figure 7 shows pendulum A and pendulum B freely suspended between the poles of identical magnets. Pendulum A is made of thick copper plate while B is made a copper plate with slots.
When the two are set to swing, it is observed that A slows down faster than B Explain this observation.
Date posted:
June 5, 2017
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Answers (1)
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Two identical copper coils P and Q are placed close to each other as shown in Figure 17. Coil P is connected to a D.C power supply and coil Q is connected to a galvanometer, G. Use this information to answer questions (a) and (b).
(Solved)
Two identical copper coils P and Q are placed close to each other as shown in Figure 17. Coil P is connected to a D.C power supply and coil Q is connected to a galvanometer, G. Use this information to answer questions (a) and (b).
(a) State and explain what would be observed on the galvanometer immediately the switch S is closed.
(b) State with reason the difference that would be noted in the observation made in question (a) if the number of turns in coils Q were doubled.
Date posted:
June 5, 2017
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Answers (1)
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Figure 15 shows a wire XY placed in a magnetic field.
(Solved)
Figure 15 shows a wire XY placed in a magnetic field.
State the direction in which the wire must be moved for the current to move in the direction shown
Date posted:
June 5, 2017
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Answers (1)
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Figure 6 represents a step-down transformer with 500 turns in the primary and 50 turns in the secondary. The turns are wound uniformly on the core. The lengths of PQ and QR are indicated.
(Solved)
Figure 6 represents a step-down transformer with 500 turns in the primary and 50 turns in the secondary. The turns are wound uniformly on the core. The lengths of PQ and QR are indicated.
Determine the p.d across PQ.
Date posted:
June 5, 2017
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Answers (1)