Apiece of iron is heated and then cooled by dropping it in water. the heat lost by the piece would be higher if a) the initial temperature and final temperature are raised by 10°c b) the initial temperature and final temperature are lowered by 10°c. c) the initial temperature is lowered and the final temperature tis raised by d) the initial temperature is raised and the final temperature is lowered by 10°c

D) the initial temperature is raised and the final temperature is lowered by 10°C

Explanation:

Heat loss:

An object tends to lose heat if its temperature is greater than the room temperature.

Heat gain:

An object tends to gain heat if its temperature is lower than the room temperature.

In our case, when a piece of iron is heated. The initial temperature of that piece is equal to the room temperature. After dropping it in water, the piece will lose heat until it reaches the final temperature which is also equal to the room temperature.

In this case, Heat gained = Heat Lost

Difference of heat lost and gained = Initial temperature - Final Temperature

= 0 degrees

This is because the Temperature of the piece of iron starts from room temperature and also ends at the room temperature while room temperature is constant.

Now, let us say that the initial temperature of the piece of iron is higher than the room temperature(Initial Temperature is raised). Also, when dropped in water. The temperature of the water is less than the room temperature(Final Temperature is dropped). In this case, the piece of iron will gain lesser heat. And it will have to lose much more heat than it gained to reach the final Temperature that is lesser than the room temperature.

Hence, in order to have the heat lost greater than the heat gained, the initial temperature must be raised and the final temperature is lowered.

In our case, Difference in heat lost and gained is equal to:

Initial Temperature - Final Temperature = (T+10°C) - (T-10°C)

= T + 10°C - T + 10°C

= 20 degrees

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it