Answer:

Explanation:
Let the linear charge density of the charged wire is given as

here we can use Gauss law to find the electric field at a distance r from wire
so here we will assume a Gaussian surface of cylinder shape around the wire
so we have

here we have


so we have

Answer:
The net charge on the shell is 30x10^-9C
Explanation:
Pls see attached file
Answer:
0.41
Explanation:
A 49 N block has a mass of 5 kg:
49/9.8
A horizontal force of 50 N giving it an acceleration of 6 m/s^2 means that 30 N is taken up by the acceleration
This leaves 20 N to take care for friction. so the coefficient of friction is:
20/49 = 0.41.
Power dissipated across any resistance is given by

now it is given that when one resistance of value 3 ohm connected the power dissipated is 4 Watt
now another identical resistance of same value is connected then the current will reduce to half of its initial value.
now power across any one resistance is given by

So now we will have

So now the power will become 1/4 times of initial power
So now the power will be

Answer:
Explanation:
The weight of the bee is:

with m the mass and g the gravity acceleration.
Electric force of the bee is related with the electric field of earth by:

with q the charge, E the electric field and Fe the electric force.
So:

Because Newton's first law we should make the net force on it equals cero:


with W the weight, Fe the electric force on the bee due earth's electric field and F the force.
So, the applied electric field should be:

The negative sign indicates that the electric field should be opposite to earth's electric field, so it should be upward.