1. Attempt any five parts:
Define the least count and zero error of vernier callipers. List any three instruments kept in the dark room of a physics laboratory. What are the four basic tools used in a physics laboratory? Write one precaution each for handling stop watch, springs and mirrors. What is the basic difference between a microscope and a telescope? Which method will you suggest for joining the materials given below? A conducting wire and a metal plate

(ii) Sunmica and table top

(iii) A CRO and its control panel What is the colour code of the following resistor? R 30 x 106, 10% n

2. Attempt any Jive parts:

(a) What measures would you take if, on entering the physics lab, you smelt gas leaking from an LPG cylinder?

(ii) State two uses of vice in a physics laboratory. Write the precautions you should take for maintaining the vice in a good working condition. The focal length of the objective of an astronomical telescope is four times the focal length of its eye-piece. If the focal length of the eye-piece is 2 cm, calculate the magnification produced by the telescope.

(ii) Draw the ray diagram for the image formed by a concave mirror when the object is at the centre of curvature of the mirror. 4 Define the units of potential difference and resistance.

(ii) Match the entities in Column I with their descriptions in Column II Column I Rheostat Switch to provide continuous current in the circuit
(2) Resistance box Switch to provide short bursts of current in the circuit Plug key Offers variable resistance Tap key Assembly of many fixed resistances Two-way key Switch to provide current flow along two different directions Give two examples where an electromagnet is used in day-to-day life.
Draw the circuit diagram for the measurement of an unknown resistance using a meter bridge and explain its working.

(e)(i) State and explain the difference between a spring balance and a beam balance.

(ii) Calculate the height of the vertical column of water supported by the atmospheric pressure. Take the density of water, d kg and 1 atm 1·013 x 10^5 Nm^-2.
What is the ideal resistance of a voltmeter Why is voltmeter always connected in parallel with the part of the circuit across which the voltage is to be measured?

(ii) Identify the kind of biasing (forward, reverse) of a junction diode for each of the figures given below. In which case is the current maximum?

<br> <img src='./qimages/11909-2f.jpg'> Match the instruments listed in Column A with their functions listed in ColumnB:

ColumnA ColumnB
Multimeter Determine time period and amplitude of an AC signal
Wheatstone Provide DC power Bridge to a circuit
CRO Check continuity of the wire
Power Supply Measure the resistance to a high degree of accuracy
From amongst the following, select the measurements that can be made by a potentiometer:

(i) direct current through resistance
e.m.f. of a cell

(iii) alternating current in a circuit