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CHAPTER 15 EXPERIMENTAL SKILLS IN PHYSICS 12TH EXERCISE 1. Which is the correct form of the graph of angle of incidence vs angle of deviation for a triangular prism during the parallax method? (a) (b) (c) (d) 2. To verify Ohm's law, a student is provided with a test resistor RT, a high resistance R1, a small resistance R2, two identical galvanometers G1 and G2, and a variable voltage source V. The correct circuit to carry out the experiment is (a) (b) (c) (d)
3. A meter-bridge is based on the principle of (a) Wheatstone bridge (b) Variation of resistance with temperature (c) Galvanometer (d) None of these 4. A multimeter is a device which can't be used as (a) an ammeter (b) a voltmeter (c) an ohmmeter (d) a magnetometer 5. A sharp image of a distant object is obtained on a screen by using a convex lens. In order to determine the focal length of the lens, you need to measure the distance between the (a) lens and the object (b) lens and the screen (c) object and the screen (d) lens and the screen and also object and the screen. 6. A student obtains a blurred image of an object on a screen by using a concave mirror. In order to obtain a sharp image on the screen, he will have to shift the mirror (a) towards the screen. (b) away from the screen; (c) either towards or away from the screen depending upon the position of the object. (d) to a position very far away from the screen. 7. In making an Ohm's law circuit, which of the following connection is correct? (a) Voltmeter in series and ammeter in parallel (b) Voltmeter in parallel and ammeter in series. (c) Voltmeter and ammeter both are in parallel (d) Voltmeter and ammeter both are in series. 8. The null point should be obtained on the metre bridge wire to get maximum accuracy at (a) the middle of the wire (b) the left end of the wire (c) the right end of the wire. (d) the 1/4 th distance from the left end. 9. A rheostat is used in an electrical circuit (a) to change the resistance of the circuit (b) to change the potential difference (c) to change the e.m.f (d) to change the current through a particular instrument. 10. A voltmeter is always connected in parallel in the experiment to determine the resistance of a given wire using ohm's law because it has (a) high resistance (b) low resistance (c) sensitive device (d) non sensitive device 11. In the experiment to determine the focal length of a concave mirror by graphical methods the u-v graph is (a) a straight line (b) a curve (c) a circle (d) an ellipse 12. For the determination of the focal length of a convex mirror, a convex lens is required because
(a) it is not possible to obtain the image produced by a convex mirror on the screen (b) a convex lens has high resolving power so it helps to measure the focal length correctly (c) a convex mirror always forms a real image which is diminished by the convex lens (d) None of these 13. Which two circuit components are connected in parallel in the following circuit diagram? (a) Rheostat and voltmeter (b) Voltmeter and ammeter (c) Voltmeter and resistor (d) Ammeter and resistor 14. A student obtained a sharp image of the grill of a window on a screen, using a convex lens. For getting better results, the teacher suggested focussing of a distant tree instead of the grill. In which direction should the lens be moved for this purpose ? (a) Away from the screen (b) Very far away from the screen (c) Behind the screen (d) Towards the screen 15. The image of a distant object is obtained on a screen by using a concave mirror. The focal length of the mirror can be determined by measuring the distance between (a) the object and the mirror (b) the object and the screen (c) the mirror and the screen (d) the mirror and the screen as well as that between the object and the screen 16. To determine the equivalent resistance of two resistors when connected in series, a student arranged the circuit components as shown in the diagram. But he did not succeed to achieve the objective. Which of the following mistakes has been committed by him in setting up the circuit? (a) Position of voltmeter is incorrect. (b) Position of ammeter is incorrect. (c) Terminals of voltmeter are wrongly connected. (d) Terminals of ammeter are wrongly connected. 17. The following circuit diagram shows the experimental setup for the study, of dependence of current on potential difference. Which two circuit components are connected in series?
(a) Battery and voltmeter (b) Ammeter and voltmeter (c) Ammeter and rheostat (d) Resistor and voltmeter 18. Zener diode works on (a) zero bias (b) reverse bias (c) forward bias (d) infinite bias 19. An LED operates under which biasing condition? (a) Forward bias (b) Reverse bias (c). Can operate both in forward and reverse bias (d) No biasing is required. 20. In a p-n junction diode (a) the current in the reverse biased condition is generally very small (b) the current in the reverse biased condition is small but the forward biased current is independent of bias voltage (c) the reverse bias current is strongly dependent on the reverse bias voltage (d) the forward bias current is very small in comparison to the reverse bias current 21. In an experiment when a PN junction diode is forward biased (a) only holes are attracted towards each other and move towards the depletion region (b) electrons and holes move away from the junction depletion region (c) width of the potential barrier decreases (d) no change in the current takes place 22. In forward-biasing V-I characteristic, the curve rises linearly after barrier voltage (a) reduces to zero (b) is overcome (c) rises to infinity (d) . None of these 23. Choose the wrong statement regarding the experiment to identify a diode, an LED, a resistor and a capacitor (a) when pointer moves in one way when voltage is applied and doesn't move when reversed and there is light emission, the item is LED (b) when pointer moves in one way when voltage is applied and doesn't move when reversed and there is no emission of light, the item is a diode (c) when pointer moves in one way when voltage is applied and not when reversed, the item is a a resistor (d) None of these 24. In an experiment p-type crystal of a p-n junction diode is connected to a positive terminal of battery and n-type crystal connected to negative terminal of battery. Then (a) diode is forward biased (b) diode is reversed biased