Earlyface

PHYSICS THEORY ANSWERS


(1ai)
(i) Voltage transformation: Transformers are used to step up or step down voltages, making them a crucial component in power transmission systems.
(ii) Efficient transmission: Transformers enable efficient transmission of power over long distances with minimal loss of energy.
(iii) Isolation: Transformers provide electrical isolation between the primary and secondary circuits, ensuring safety and preventing interference.

(1aii)




(1b)
Area = Length x Width
= 100 m x 500 m
= 50,000 m²

Area (acres) = Area (m²) / 4047 m²/acre
= 50,000 m² / 4047 m²/acre
= 12.35 acres

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(2)


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(3a)
A rolling wheel

(3b)
Given:
F1 = 8 N (acting horizontally)
F2 = 5 N (acting vertically, at a right angle to F1)

Using the Pythagorean theorem:

F = √(F1² + F2²)
= √(8² + 5²)
= √(64 + 25)
= √89
= 9.43 N

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(4)


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(5a)
Heat capacity of a body is the amount of heat energy required to change the temperature of the body by a given amount. It is measured in joules per kelvin (J/K).

(5b)
Q = mcΔT

where:
Q = heat energy (in joules, J)
m = mass of water (in kilograms, kg)
c = specific heat capacity of water (in J/kgK)
ΔT = temperature change (in kelvin, K)

Given values:
m = 100 g = 0.1 kg (converted to kilograms)
c = 4200 J/kgK
ΔT = 20°C = 20 K (since 1°C = 1 K)

Plugging in the values:

Q = 0.1 kg × 4200 J/kgK × 20 K
= 8400 J
= 8.4 kJ

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(6)
(i) Atmospheric conditions: During the day, the atmosphere is more turbulent and chaotic, with warm air rising and cooler air sinking. This turbulence scatters sound waves, making them less focused and less intense. At night, the atmosphere is generally calmer and more stable, allowing sound waves to travel more directly and with less scattering.

(ii) Temperature gradient: During the day, the ground and surrounding objects absorb and radiate heat, creating a temperature gradient that affects sound wave propagation. At night, the temperature gradient is reduced, allowing sound waves to travel more efficiently.

(iii) Humidity: Daytime humidity can absorb and scatter sound waves, reducing their intensity. Nighttime air is often drier, allowing sound waves to travel farther without attenuation.

(iv) Background noise: Daytime environments are often filled with background noise from human activity, traffic, and other sources. At night, this background noise is reduced, making sounds more prominent and audible.

(v) Psychological factor: Our brains are more sensitive to sounds at night due to the quiet environment, making us more aware of subtle sounds that might be masked during the day.

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(7)


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(8.)

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(9)
(i) Preparing the spoon: The iron spoon is thoroughly cleaned and polished to remove any dirt, oil, or other substances that might interfere with the electroplating process.

(ii) Electrolyte solution: A gold electrolyte solution is prepared, which contains gold ions (Au+) dissolved in a chemical solution.

(iii) Setting up the electroplating cell: The spoon is immersed in the gold electrolyte solution, and an electric current is passed through the solution using an anode (positive electrode) and a cathode (negative electrode). The spoon acts as the cathode.

(iv) Redox reaction: When the electric current is applied, a redox (reduction-oxidation) reaction occurs. Gold ions (Au+) in the solution are reduced (gain electrons) and deposited onto the surface of the spoon (cathode).

(v) Gold deposition: The gold ions are continuously deposited onto the spoon's surface as the electric current is maintained, forming a thin layer of gold.

(vi) Monitoring and controlling: The electroplating process is carefully monitored and controlled to ensure a uniform and desired thickness of the gold layer.

(vii) Rinsing and drying: Once the electroplating process is complete, the spoon is removed from the solution, rinsed with water, and dried to reveal a thin, shiny layer of gold.

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(12)


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(13)


 

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(14)


 

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