Correct Answer: C. 2\(\theta\)

Explanation

a. Fiber optics is a technology that uses light to transmit data over long distances. Fiber optic cables are made of thin, flexible strands of glass or plastic that can carry a large amount of data at very high speeds.

b. - Higher bandwidth: Optical fibers can carry a much larger amount of data than copper cables. This is because light travels much faster than electricity and optical fibers can carry more light signals than copper cables can carry electrical signals.

- Longer distances: Optical fibers can transmit data over longer distances than copper cables without signal loss. This is because light signals are less attenuated in optical fibers than electrical signals are in copper cables.

- Immunity to interference: Optical fibers are immune to electrical interference, which can cause problems with copper cables. This is because optical fibers transmit light signals, which are not affected by electrical fields.

- Security: Optical fibers are more secure than copper cables because they are difficult to tap. This is because light signals cannot be detected without damaging the optical fiber.

- Durability: Optical fibers are more durable than copper cables. They are less susceptible to damage from moisture, temperature fluctuations, and physical impact.

- Cost-effectiveness: Optical fibers are becoming more cost-effective than copper cables, especially for high-bandwidth applications. This is because the cost of manufacturing optical fibers has decreased significantly in recent years.

Correct Answer: A. 50 J

Correct Answer: C. it is formed by actual intersection of rays

Explanation

\(h = \frac{1}{2} gt^2\) t = \(\sqrt{\frac{2h}{g}}\)

= \(\sqrt{\frac{2 \times 45}{10}}\) = 3s

Horinzntal distance = vt = 10 x 3 = 30m

Explanation

(a) Fission: Nuclear reaction in which a heavy nucleus is bombarded with neutrons and split into approximate equal parts emitting neutrons and releasing large amounts of energy.

Fusion: Nuclear reaction between two light nuclei forming a heavier nucleus with the release of a large amount of energy.

(b) Advantages of Fusion over Fission:

(1)By - products are non-radioactive. (2) Easily achieved with lightest elements so that nuclear repulsion is easily overcome as nuclei approach each other. (3) Raw materials are cheaply available.

Why fusion is not normally used : Very high temperature is required to overcome coulomb repulsive forces between the two light nuclei. It is difficult to get materials that will withstand such high temperature. Mathematically,

\(T^{\frac{1}{2}} = \frac{0.693}{\lambda}\), where \(\lambda\) is the decay constant.

Decay constant = \(\frac{\text{no of atoms disintegrating per sec}}{\text{no of atoms in the source at that instant}}\)

Isotopes: Isotopes of an element are atoms which have the same proton numbers/atoms number but different nucleon numbers/mass number.

Decay scheme: \(^{238} _{92} U \to ^{234} _{90} Th + ^{4} _{2} He + Energy\)

\(^{234} _{90} Th \to ^{234} _{91} Pa + ^{0} _{-1} e + Energy\)

\(^{234} _{91} \to ^{0} _{-1} e + ^{234} _{92} + Energy\)

(d) Uses of radioisotopes:

(1) Radio therapy (2) Radio dating (3) Used as tracers and preservatives in agriculture.

Explanation

(a) The princle on which lighting in a fluorescent operation is electrical discharge through a gas at low pressure and at high voltage.

(b) The colour of light produced in a fluorescent tube depends on factors;

(i) coating inside the tube; and (ii) the nature ype of gas in the tube.

Correct Answer: C. 12V

Correct Answer: A) 4.99 x 10⁵ Nm^-2

Correct Answer: A. alpha and beta particles