Answer:
The number of bright fringes per unit width on the screen is, 
Explanation:
If d is the separation between slits, D is the distance between the slit and the screen and 
is the wavelength of the light. Let x is the number of bright fringes per unit width on the screen is given by :
is the wavelength
n is the order
If n = 1,
So, the the number of bright fringes per unit width on the screen is 
. Hence, the correct option is (B).
"1 watt" means 1 joule of energy per second.
75 W means 75 joules/sec .
Energy = (75 Joule/sec) x (12 min) x (60 sec/min)
Energy = (75 x 12 x 60) (Joule-<em>min-sec</em> / <em>sec-min</em>)
<em>Energy = 54,000 Joules</em>
Answer:
It's impossible for an ideal heat engine to have non-zero power.
Explanation:
Option A is incomplete and so it's possible.
Option B is possible
Option D is related to the first lae and has nothing to do with the second law.
Hence, the correct option is C.
The ideal engine follows a reversible cycle albeit an infinitely slow one. If the work is being done at this infinitely slow rate, the power of such an engine is zero.
We can also stat the second law of thermodynamics in this manner;
It is impossible to construct a cyclical heat engine whose sole effect is the continuous transfer of heat energy from a colder object to a hotter one.
This statement is known as second form or Clausius statement of the second law.
Thus, it is possible to construct a machine in which a heat flow from a colder to a hotter object is accompanied by another process, such as work input.
