Nuclear Physics

To solve the problem, we need to understand the role of heavy water in a nuclear reactor.

1. Function of a Moderator in a Nuclear Reactor:
In a nuclear reactor, a moderator is a substance used to slow down the fast-moving neutrons produced during fission. Slower (thermal) neutrons are more likely to cause further fission reactions with fissile material like Uranium-235, thus maintaining a sustained and controlled chain reaction.

2. Why Heavy Water?
Heavy water ( ) is an excellent moderator because: - It slows down neutrons without capturing them (unlike ordinary water which absorbs more neutrons). - It helps sustain the chain reaction even with natural (unenriched) uranium due to its low neutron absorption cross-section.

3. Eliminating Incorrect Options:
- "It controls the energy released in the reactor" → Incorrect: control rods do this, not the moderator.
- "It absorbs neutrons and stops chain reaction" → Incorrect: moderators must not absorb neutrons.
- "It cools the reactor faster" → Incorrect: that’s the function of a coolant, not a moderator.
- "It slows down the fast moving neutrons" → Correct.

Final Answer:
Heavy water is used as a moderator because it slows down the fast moving neutrons.

Step 1: Identifying the Conducting Path
- Given that the diodes are ideal, is forward biased (conducting), and is reverse biased (non-conducting).
- The circuit simplifies to a series circuit with a resistor connected to a battery.

Step 2: Calculating the Current By Ohm’s Law:

Step 3: Power Delivered by the Battery Power is given by: Thus, the correct answer is .

Step 1: Understanding Amplitude Modulation In amplitude modulation (AM), the resultant signal consists of the carrier frequency and sidebands. The sideband frequencies are given by: where:
- kHz = MHz (carrier frequency),
- kHz (modulating signal frequency).

Step 2: Calculating Sideband Frequencies Since the question asks for one possible frequency, the correct answer is: Thus, the correct answer is .

The energy released in the decay process involves the conversion of mass into energy according to Einstein's relation . Given the mass number 236 and the energy of the alpha particle, the ratio can be calculated based on the energy equivalence and decay mechanism.

Step 1: The total energy released during the process of an -particle decay can be related to the ratio of mass numbers and energy based on decay theory. Using the formula derived from the decay laws, we calculate the total energy as: Thus, the correct answer is .