Answer:
initial magnetic field 1.306 T
Explanation:
We have given area of the conducting loop 
Emf induced = 1.2 volt
Initial magnetic field B = 0.3 T
Time dt = 0.087 sec
We know that induced emf is given by 


So initial magnetic field = 1.606-0.3= 1.306 T
Answer:
v = 5.75 x 10⁶ m/s
Explanation:
The radius (r) of the circular orbit taken by a charged particle is related to its speed perpendicular to a magnetic field of strength B, and is given by
r =
--------------(i)
Where,
q = charge of the particle
m = mass of the particle
Making v subject of the formula in equation (i) above gives
v =
-------------------(ii)
Given;
r = 20cm = 0.2m
B = 0.3T
v = unknown
q = charge of proton = 1.6 x 10⁻¹⁹ C
m = mass of the proton = 1.67 x 10⁻²⁷kg
Substitute the values of m, q, B and r into equation (ii) above to get;
v = 
Solving for v gives:
v = 5.75 x 10⁶ m/s
Therefore, the velocity of the proton is 5.75 x 10⁶ m/s
A because the earth have four season and four name for its tilt around the sun. one aphelion prehelion but spring and fall is balance. when its summer in the north it is cold in the south because of son rays
The new force between the charges when the distance become 2d will be F'=4F
<h3>What is electrostatic force?</h3>
When two charged particles are separated by the distance d then the force of attraction or repultion acts on the charged particle depending upon the nature of the charge whether it is positive or negative.
The formula for the electrostatic force is given by

Now if the value of d becomes 2d then the formula will become:



Hence the new force between the charges when the distance become 2d will be F'=4F
To know more about electrostatic force follow
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First of all, we need to write the First Law of thermodynamics assigning the correct sign convention:

where
is the change in internal energy of the system
Q is the heat absorbed/released
W is the work done
and the signs are assigned based on whether there is an increase in the internal energy or not. Therefore:
Q is positive if it is absorbed by the system (because internal energy increases)
Q is negative if it is released by the system (because internal energy decreases)
W is negative if it is done by the system on the surrounding (because internal energy decreases)
W is positive if it is done by the surrounding on the system (because internal energy increases)
Using these definitions, we can now fill the text of the question:
When a system is heated, heat is ABSORBED by the system. The amount of heat added is given a POSITIVE sign. When a system is cooled, heat is RELEASED by the system. The amount of heat is given a NEGATIVE sign. If a gas expands, it must push the surrounding atmosphere away. Thus, work is done BY the system and is given a NEGATIVE sign. If a gas is compressed, then work is done ON the system. This work is given a POSITIVE sign.