## Sunday, 20 March 2016

### WORKSHEET#2 ELCTRIC FLUX CBSE CLASS12 PHYSICS QUESTIONS WITH KEY

1. If the radius of the Gaussian surface enclosing a charge is halved, how does the electric flux through the Gaussian surface change?
No change
2. A charge Q micro coulomb is placed at the centre of a cube. What would be the flux through one face?
Q/6ε0

3. If the E=8i+4j+3k NC-1, Calculate the electric flux through a surface of area 100 m2 lying in x-y plane
ɸ= EScosθ =30 Nm2c-1 ii.15 Nm2C-1
300 Nm2C-1

4.The electric field in a certain region of space is (5i+4j-4k) x 105 N/C. Calculate the electric flux due to this field over an area of (2i-j) x 10-2 m2.

ɸ=E.S = 6 x 103 Nm2C-1

5. A sphere of radius 0.03m has a point charge of q = 7.6μC is located at its center. Find the electric flux
through it.

Φ=q/ɛ0 = 8.6 x 105Nm2C-1

6. A point charge of 17.7μC is located at the centre of a cube of side 0.03m. Find the electric flux through each face of the cube.

1/6φ=1/6q/ɛ0 = 3.3 x 105Nm2C-1

7. 5,000 lines of force enter a certain volume of space and three thousands lines emerged from it. What is the total charge in Coulomb within the volume?

-1.77 x 10-8 C

8.  A spherical Gaussian surface encloses a charge of 8.85 x 10-8 C
i. Calculate the electric flux passing through the surface
ii. If the radius of the Gaussian surface is doubled, how would the flux change?

i)104 Nm2C-1 ii) 104 Nm2C-1

9.The electric field in a region is given by E=E0x/b i’ find the charge contained in the cubical volume bounded by the surfaces x=0,x=a, y=0,z=0 and z=a. Take E0=5 x 103 Nc-1, a=1cm and b=2cm.
φE=φL

10.An electric field (2i + 3j ) x 103 NC-1 exists in a region. Calculate the electric flux linked with a square of side 0.5m held parallel to a) y-z plane b) x-y plane.

a)24 Nm2 C-1  b) 0.5 Nm2 C-1