Explanation

The direction of the induced emf is predicted by Lenz's Law.

It states that the induced emf always acts to oppose the change causing it.

Explanation

Mercury is used as a thermometric fluid because it has several ideal properties:

1. High Boiling Point (B.P)

   • Mercury doesn't evaporate easily, which makes it suitable for measuring high temperatures.

2. Low Freezing Point (not high M.P)

   • Mercury has a low melting point (−38.83°C), which helps in measuring low temperatures, though this limits it in very cold environments.

3. Stable and Uniform Coefficient of Expansion

   • Mercury expands uniformly with temperature, which gives accurate and consistent readings.

4. Visibility and Non-wettability

   • Mercury is shiny and opaque, so it's easy to see in a glass tube.

   • It doesn't stick to glass, which keeps the readings clean and precise.

Explanation

Glass is an insulator because it does not allow electricity to pass through easily.

Silver, copper, and aluminum are conductors, meaning they allow electric current to flow.

Explanation

Explanation

Speed of sound in air is proportional to the square root of absolute temperature v ∝ √T.

To double the speed, temperature must increase 4 times in Kelvin:

At 27°C = 300 K → 4 × 300 = 1200 K → 1200 - 273 = 927°C

Explanation

A thermos flask is designed to reduce heat transfer through all three methods:

• Conduction: The flask has a vacuum insulation, which eliminates conduction through the container.
• Convection: The flask's design and vacuum insulation prevent convective heat transfer.
• Radiation: The flask's reflective coating minimizes radiant heat transfer.

Explanation

For projectile motion, two complementary angles θ and 90° - θ give the same range if the initial velocity is constant.

Since 10° + 80° = 90°, the angles 10° and 80° are complementary and will have equal ranges.

Explanation

A step-up transformer increases the voltage of the input signal, resulting in a higher voltage output.

This is achieved by having more turns in the secondary coil than in the primary coil.

Explanation

The guitar is a musical instrument of the chordophone family.

The standard guitar has following six strings:

1. E

2. A

3. D

4. G

5. B

6. E

Explanation

ln3 means the natural logarithm of 3 (log base e).

Its approximate value is 1.0986.