NATIONAL OPEN UNIVERSITY OF NIGERIA
14/16 AHMADU BELLO WAY, VICTORIA ISLAND, LAGOS
SCHOOL OF SCIENCE AND TECHNOLOGY
MARCH/APRIL 2014 EXAMINATION
COURSE CODE: PHY320
COURSE TITLE: PHYSICS LABOURATORY
TIME ALLOWED: 2HOURS
INSTRUCTION: ANSWER QUESTION ANY FOUR QUESTIONS
QUESTION ONE
- State the maximum power transfer theorem
- Plot a graph between load resistance RL against the power transferred, for several values between 1 kΩ , 5 kΩ,10 kΩ,15 kΩ 20 kΩ for the circuit Fig 1 :
Fig 1
- What is the efficiency of the circuit at the maximum power transfer condition?
- State the precautions needed to verify this theorem.
QUESTION TWO
In an experiment involving A NTC thermistor, the table 1 below was obtained;
Temp (C) | 20.20 | 22.80 | 26.95 | 30.95 | 32.20 | 36.30 | 38.70 | 43.40 | 45.20 |
R(kohms) | 11.90 | 10.80 | 9.17 | 7.87 | 7.50 | 6.43 | 5.89 | 4.99 | 4.69 |
Table 1
- Plot the graph of 1/T ( ̊C-1) against log R
- Find the slope of the graph
- State 2 precautions you must ensure while carrying out this experiment.
- Name 4 apparatus needed for this experiment.
- List a few metals, semiconductors, and insulators that you are familiar with.
- Distinguish between metals, semiconductors and insulators in terms of energy gap.
QUESTION THREE
- Distinguish between an active and a passive network
- With a suitable ray diagram, explain the principle of Young’s double slit experiment.
- State two precautions you would take to ensure accurate results in Young’s double-slit experiment.
- A double-slit source with slit separation 0.2 mm is located 1.2 m from a screen. The distance between successive bright fringes on the screen is measured to be 3.30 mm. What is the wavelength
of the light?
QUESTION FOUR
- State the reciprocity theorem.
- State 2 precautions you must ensure while carrying out this reciprocity experiment.
- The formula for electrical current per ohms law is?
- A path between two or more points along which an electrical current can be carried is called a ____________
- Electric current is the flow of _______ from a ______ polarity to a _________ polarity.
In a simple DC circuit with a constant voltage, where the resistance increases current will ______________
QUESTION FIVE
- Describe how an Op-amp may be used as :
- Voltage to current converter.
- Current to voltage converter.
- an integrator.
- a differentiator.
(b)
(i) Outline the principle of the measurement of magnetic flux density using the op-amp.
(ii) State the precautions you would take in an experiment to measure electric charge using an op amp.
QUESTION SIX
(a)
(i) Distinguish between a positive and negative lens.
(ii) With suitable ray diagrams, explain the terms focus and focal length of a converging and diverging lens.
(b)
(i) In an experiment to determine the focal length of a converging lens, was plotted on the horizontal axis and on the vertical axis (u and v are the object and image distances respectively). Explain, with suitable equations, how you would use this graph to obtain the power, focal length and linear magnification of the lens.
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