It is D, a paint can carried up a ladder.
Answer:
Part a)

Part b)

Explanation:
Resistance of the solenoid is given as
R = 4.10 ohm
now we have

here we know that



now from above formula


Part a)
now we know that it is wounded over the solenoid
so here we can say



Part b)
now length of solenoid is given as



It is considered a substance because it has a uniform and definite composition.
Answer:
See explanation
Explanation:
Electric field strength;
E = kq/d^2
k= coulombs constant
q= magnitude of charge
d = distance if separation
If
d is constant
q = 2q
Then;
E = 2 kq/d^2
Hence, the electric field strength will double.