Electrostatics Lab Report

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- In this the initially recorded charge was -19.27 nC.

- During second attempt it was -19.19 nC

- Third time it was -19.19 nC

- Fourth time it was -19.00 nC

- Fifth time it was -18.96 nC

During this experiment the charge decrease by time, charge may be lost in the air or it may touch to the table or wall of the can.

- Polarization of objects

In this part when negatively charged rod bring near to neutral pith ball, the ball attracted to ball.

- What happens is that when negatively charged rod near to the pith ball, the negative charge repels the electrons on that side of the ball.

These repelled electrons migrate to the opposite side of the ball, the side opposite the negatively charged rod. This leaves the part of the ball facing the rod slightly positively charged. As we know, positive and negative charges attract, and therefore the now positve side of the ball is attracted to the negatively charged rod, even though at the start the pith ball was neutral.

- Estimation of Coulomb constant

In this experiment two pith balls are used to find the force between two charged bodies explained by coulomb’s law.

In this part we Charged both balls with the same charge (if the two balls are touched together when they are charged we will assume that the total charge will distribute equally between the two balls) and then find the sepration of balls

i.e.

Fe = k q1q2 / R2

As q1 = q2 = 25.0 nC

M = 6.4 × 10-4 kg

r = 1.00 cm

l = 4.65 cm

g = 9.80 m/s2

T sinθ = Fc

Tcosθ = w

w = mg

Tr/2L = mg

T = 6.4 ×10-4 * 9.8*2*0.0465[pic 4]

- m

= 5.83×10-2 N

Fe = 6.26×10-3 N

Fc = k q1 q2 [pic 5]

R2

k = 6.26× 10-3 *0.01*0.01[pic 6]

2.78*2.78 ×10-18

k= 8.11×109 N.m2/C2

Analysis : In charging by friction the grey rod gain 4.89 × 1011 electron and white rod loose 4.12 × 1011 electrons.

And in charging by induction, charges loose by some external factor like in air or may be touching by wall of can. During charging by conduction same thing happened with charges.

In Polarization of objects the neutral ball attracted by negatively charged rod (as explained above). for Coulomb constant we got the value k= 8.11×109 N.m2/C2 . Which is nearly equal to the theoretical value.