Answer:
1) The strength of the electromagnet increases → Place a magnetic core inside the coil of wire
2) The electromagnet turns off → Turn off the battery supply
3) The poles of the electromagnet reverse → Change the direction in which the current flows
Explanation:
when current passes through a coil it behaves a an electromagnet.
Magnetic field strength is given by
B = μ N I
N is no of turns and
I is the current through coil
μ is permeability of the medium or core in the coil.
1). Magnetic core increase permeability μ so it will strengthen magnetic field:
B = <u>μ</u> N I
2). When the battery turns off current becomes zeroi.e I=0
So B = μ N * 0
⇒ B = 0
so electromagnet turns off
3). Direction of magnetic field can be determine by right hand rule, i.e curl the fingers in the direction of current, thumb will point in the direction of north pole.
so changing current direction will change direction of magnetic field.
The strength of the gravitational field is given by:

where
G is the gravitational constant
M is the Earth's mass
r is the distance measured from the centre of the planet.
In our problem, we are located at 300 km above the surface. Since the Earth radius is R=6370 km, the distance from the Earth's center is:

And now we can use the previous equation to calculate the field strength at that altitude:

And we can see this value is a bit less than the gravitational strength at the surface, which is

.
Answer:
As much wood as a woodchuck could chuck, If a woodchuck could chuck wood.
Explanation:
<span>Answer: Burrhus Frederic Skinner's Operant Conditioning.
</span><span>B.F. Skinner believed that to understand behavior, in the best way, is to look at the root causes or reasons of an action and its outcomes.
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Skinner proposes the Law of Effect-Reinforcement. Here,he differentiated the positively reinforced behavior or the strengthened behavior, the negatively reinforced behavior (removal of the unpleasant experience), and weakened behavior because of punishment.
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In positive reinforcement, behavior is strengthened through providing an outcome, an effect that an individual finds rewarding. Negative reinforcement also strengthens behavior because the unpleasant experience was removed. Punishment on the other hand is an opposite to reinforcement. Instead of increasing the response, it eliminates it or weakens it.
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That is true Step by step: