Correct Answer: A. Hygrometer

Explanation

The instrument used to measure relative humidity is a hygrometer. Relative humidity is the amount of moisture in the air compared to the maximum amount of moisture the air could hold at the same temperature. A hygrometer is a device used for measuring the moisture content in the atmosphere, soil, or confined spaces.

Correct Answer: C. \(45^0\)

Explanation

Maximum Range R = \(\frac{u^2sin2\theta}{g}\)

maximum height H = \(\frac{u^2sin^2\theta}{2g}\)

But R : H = 4

\(\frac{u^2sin2\theta}{g}\) : \(\frac{u^2sin^2\theta}{2g}\) = 4

\(\frac{u^2sin2\theta}{g} \times\frac{2g}{u^2sin^2\theta}\) = 4

\(\frac{2sin2\theta}{sin^2\theta}\) = 4

since 2sinΘ = 2sinΘcosΘ

\(\frac{2 \times 2sin\theta cos\theta}{sin^2\theta}\) = 4

\(\frac{4sin\theta cos\theta}{sin^2\theta}\) = 4

\(\frac{sin\theta cos\theta}{sin^2\theta}\) = 1

\(\frac{cos\theta}{sin\theta}\) = 1

\(\frac{sin\theta}{cos\theta}\) = 1

\(tan \theta\) = 1

\(\theta = tan^{-1}1\) = 45°

Correct Answer: A. 1.25m

Explanation

u = 0, g = 10 \(ms^2\), v = 5 m/s, h = ?

From \(v^2 = u^2 + 2gh\)

⇒ \(5^2 = 0^2 + 2 × 10 × h\)

25 = 0 + 20h

25 = 20h

Therefore, h = \(\frac{25}{20}\) = 1.25m

Correct Answer: B. 160.0m

Explanation

Distance between X and Y is the area of rectangular portion of the velocity-time graph. XY = 40

Explanation

a. – Extrinsic semiconductors are produced by adding impurities into pure semiconductors, while intrinsic semiconductors are always present in their most pure state.

- Extrinsic semiconductors have a high electrical conductivity in comparison to other materials at room temperature, while intrinsic semiconductors have a low electrical conductivity.

- In intrinsic semiconductors, the number of electrons and holes is equal, however, this is not the case in extrinsic semiconductors.

- Temperature alone determines the behavior of intrinsic semiconductors, whereas extrinsic semiconductors are influenced by both temperature and the number of impurities present.

- n-type and p-type semiconductors are two categories of extrinsic semiconductors, while intrinsic semiconductors are not further subdivided.

b.

Correct Answer: A. has a high susceptibility.

Explanation

Ferromagnetic materials are characterized by having a high susceptibility, which means they are strongly attracted to magnetic fields. When placed in a magnetic field, ferromagnetic materials become magnetized and can themselves exhibit strong magnetic properties, attracting other magnetic materials. Ferromagnetic materials, such as iron, nickel, and cobalt, are commonly used in the construction of permanent magnets and electromagnets due to their strong response to magnetic fields.

Correct Answer: A. Step-up transformer

Explanation

The device associated with alternating currents (AC) only from the provided options is the step-up transformer. Step-up transformers are specifically designed to work with alternating currents and are used to increase voltage levels in AC systems.

Explanation

a. Strain energy is the potential energy stored within an elastic material as a result of its deformation caused by external forces.

b. Energy stored E = \(\frac{1}{2}Fe\)

Young Modulus = \(\frac{ Stress}{ Strain}\) = Y

Stress = \(\frac{Force}{Area} = \frac{(F)}{(A)}\)

Strain = \(\frac{ Extension}{Original Length} = \frac{(e)}{(l)}\)

Y = \(\frac{F}{A}\div \frac{e}{l}\)

Y = \(\frac{F}{A} \times \frac{l}{e}\)

F = \(\frac{YAe}{l}\)

Therefore, Energy stored E = \(\frac{1}{2}\frac{YAe}{l}\times e\)

E = \(\frac{YAe^2}{2l}\)

Correct Answer: C. concave mirror

Explanation

Concave mirrors are curved inwards and produce a magnified image of the object placed within its focus and pole. This is why dentists use concave mirrors to examine teeth, as it allows them to see the teeth in more detail.

Correct Answer: C. 50J

Explanation

\(M_{bullet}\) = 0.05kg, \(V_{bullet}\) = 200m/s, \(M_{block}\) = 0.95kg and \(V_{block}\) = 0

for an inelastic collision

\(M_{bullet} \times V_{bullet} + M_{block} \times V_{block} = (M_{bullet} + M_{block})\)v

0.05 x 200 + 0.95 x 0 = ( 0.05 + 0.95)v

10 + 0 = v

v = 10m/s

K.E of the block = \(\frac{1}{2}mv^2\)

K . E = \(\frac{1}{2} \times(0.05 + 0.95) \times10^2\) ( bullet now part of the block)

K . E = \(\frac{1}{2} \times1 \times100\)

= 50J