Using Ampere's Law, the magnetic field produced inside this solenoid is given by
B = uo N I / h
where uo is the vacuum permeability, N is the number of turns in the solenoid and h is the length of the solenoid. Earth's magnetic field is around 50 microteslas in North America thus the current needed in the solenoid is
I = B h / (uo N) = (50 E-6 ) (4) / ((4 pi E-7)(6000) ) = 0.026 A
I = 26 mA
So you need a current of around 26 mA.
Answer:
Turn the heater on
Explanation:
There are two main forces involved in a balloon flight
The downward force is the total weight of the balloon: the air it contains, the gas bag, the basket, the passengers, etc.
The upward force is the weight of the of the air the balloon displaces.
During level flight
,
buoyant force = weight of displaced air - total weight of balloon
If you increase the temperature of the air in the bag, the air molecules spread out and leave through the bottom of the bag.
The balloon still has the same volume, so the weight of displaced outside air stays the same.
However, the balloon has lost some hot inside air, so its total weight decreases.
The upward force is greater than the downward force, so the balloon rises.
Answer:
Explanation:
b = b₀ cos ω t
When t = 0 , magnetic field will be b₀ and positive or directed into the page . This is the maximum value of magnetic field. As times goes ahead , magnetic field decreases so magnetic flux decreases . The induced emf or current will be such that it will opposes this reduction of magnetic field. Hence , current in clockwise direction will be generated in the coil which will generate magnetic flux into the paper.
In this way current will be induced clockwise.
Its actually C. I did the question on USA test prep and it said the correct answer was C.