SAFETY IN THE PHYSICS LABORATORY

In the physics laboratory, carelessness can lead to accidents causing injury to you or to your neighbor. Some instruments are costly. If such an instrument is damaged in an accident, it can paralyze the work of the whole class. Proper handling of apparatus and other materials can prevent majority of accidents.

Remember the following points and act on them, while working in the physics laboratory.

(i) Put off the gas to extinguish the flame of a burner. Do not use any solid or liquid for this purpose (like putting a cap or pouring water as for extinguishing burning coal).

(ii) Do not throw any broken glass ware, etc. in the sink. Such things should be thrown into the waste basket.

(iii) Do not talk to other students in the laboratory while performing the experiment. In case you have any difficulty, consult your tutor. Of course, if you are a team of two or three students working on same experiment on the same apparatus, you can talk about the experiment among yourselves. Each member of the team should take turns to take observations.

(iv) Never test whether a wire is carrying current by touching it, Use a tester screwdriver or/ a voltmeter of Appropriate range.

(v) Whenever a sharp instrument is used, be careful not to cut or puncher your skin, e.g. while using a pair of blades to make a narrow slit.

(vi) While using a delicate instrument, e.g. a sensitive galvanometer, be careful not to pass a high current in it, which may burn it out. While using it to find a null point, use a low resistance shunt or a high series resistance initially.

When you approach the null point, then remove it to make the instrument sensitive and make fine adjustment of the null point.

(vii) Take care not to wet any instrument, unless it is part of the experiment itself

Comments

Young’s Modulus ‘Y’ By Searle’s Method

Aim: To determine Young’s modulus of elasticity of the material of a given wire by Searle’s method. Procedure: i. Arrange the experimental set up as shown in diagram. Attach a zero load (slotted hanger it self) and dead load (E) to the frames of the experimental wire and dummy wire respectively so that the wires become free of kinks and remain vertically straight. ii. With the help of micrometer screw gauge, find the correct diameter of the wire at three different places. At every place two readings of the micrometer are taken while holding it in one position and another perpendicular to it by rotating through 90°. iii. In all, six readings of the diameter of the wire are taken. Hence mean diameter and radius of the wire is found out. iv. Adjust the spirit level so that the air bubble is at the centre. Note down the reading of the micrometer screw (M) attached to it. This is zero reading. (This contains main scale reading ...

Qualitative analysis test

To detect one cation and one anion from the following: (Insoluble salts to be excluded) Apparatus: Micro test-tubes with stand, test tube holder, kerosene burner, W-tube, well plate, dispensing bottles, china dish, cotton swabs, charcoal cavity, W. Tube etc. Chemicals: 6MH2 SO4, 6MHCl, lime water, sodium carbonate, sodium metal, BaCl2 solution, KMnO4 solution, KI solution, starch solution, acetic acid Introduction: The inorganic qualitative analysis involves the identification of ions present in a sample. The salt consists of anion and cation. The basis of identification is the observed chemical behaviour of the components. The salt analysis may be systematically carried out in the following three steps: i) Preliminary examination ii) Detection of anions and iii) Detection of cations Preliminary examination: First we proceed to examine the physical properties of the salt. This is followed b...

Spectrometer I - Refractive index of the prism.

PROCEDURE: I. To determine the angle of the prism 1. The preliminary adjustments for telescope, prism and the collimator are done. 2. The slit is illuminated by a sodium vapour lamp. The prism table is mounted vertically. 3. The refracting edge of the prism placed facing the collimator. 4. The image on one side is seen through through the telescope and the vernier readings (R1) are noted. 5. The image on other side is seen through through the telescope and the vernier readings (R2) are noted. 6. 2A = R1  R2  hence the angle of the prism ‘A’ is determined using A =  II. To determine the angle of minimum deviation 1. The edge of the prism is placed facing away from the collimator. 2. The refracting image is obtained in the telescope. The prism table is slowly rotated. 3. The image moves, then stops and turns back. The position of the image where the image stops and turns back is the minimum deviation. 4. The vernier readings (R3) are noted at this position and the direct ray reading...

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