Energy Conversions

What energy conversion takes place in an electric bulb?
a) Electrical → Chemical
b) Electrical → Light + Heat
c) Heat → Electrical
d) Light → Electrical
✅ b) Electrical → Light + Heat
Explanation: The filament converts electricity to light and some heat.

What is the energy change in a microphone?
a) Sound → Electrical
b) Electrical → Sound
c) Electrical → Mechanical
d) Light → Sound
✅ a) Sound → Electrical
Explanation: Microphones convert sound vibrations into electrical signals.

What type of energy is stored in food?
a) Mechanical
b) Chemical
c) Heat
d) Sound
✅ b) Chemical
Explanation: Energy in food is stored in chemical bonds.

The energy conversion in a solar panel is:
a) Chemical → Electrical
b) Thermal → Mechanical
c) Solar → Electrical
d) Electrical → Chemical
✅ c) Solar → Electrical
Explanation: Solar panels use photovoltaic cells to convert sunlight to electricity.

A loudspeaker converts:
a) Sound → Mechanical
b) Electrical → Sound
c) Chemical → Light
d) Light → Mechanical
✅ b) Electrical → Sound
Explanation: Electrical energy is converted to vibrations producing sound.

What is the energy change in a battery-powered torch?
a) Heat → Light
b) Chemical → Light
c) Chemical → Electrical → Light
d) Mechanical → Light
✅ c) Chemical → Electrical → Light
Explanation: Stored chemical energy flows as electric current, producing light.

What conversion happens in a hydroelectric power plant?
a) Solar → Electrical
b) Mechanical → Chemical
c) Potential → Kinetic → Electrical
d) Thermal → Mechanical
✅ c) Potential → Kinetic → Electrical
Explanation: Water falls (potential → kinetic) and turns turbines to generate electricity.

Which form of energy is stored in a stretched rubber band?
a) Thermal
b) Kinetic
c) Elastic potential
d) Electrical
✅ c) Elastic potential
Explanation: Due to deformation, potential energy is stored.

In photosynthesis, the energy conversion is:
a) Light → Chemical
b) Heat → Chemical
c) Chemical → Light
d) Light → Thermal
✅ a) Light → Chemical
Explanation: Plants convert solar energy to chemical energy in glucose.

In a generator, the energy conversion is:
a) Electrical → Mechanical
b) Chemical → Heat
c) Mechanical → Electrical
d) Electrical → Magnetic
✅ c) Mechanical → Electrical
Explanation: Turbines rotate the coil, inducing electricity via magnetic field.

In a fan, energy is converted from:
a) Electrical → Mechanical
b) Heat → Light
c) Mechanical → Sound
d) Sound → Electrical
✅ a) Electrical → Mechanical
Explanation: Electrical energy rotates the blades (mechanical motion).

In an electric iron, energy conversion is:
a) Electrical → Mechanical
b) Electrical → Heat
c) Heat → Electrical
d) Heat → Mechanical
✅ b) Electrical → Heat
Explanation: Heating elements convert electric energy to thermal.

The primary energy transformation in a car engine is:
a) Heat → Electrical
b) Chemical → Mechanical
c) Mechanical → Sound
d) Electrical → Mechanical
✅ b) Chemical → Mechanical
Explanation: Fuel combustion drives pistons to move the vehicle.

A windmill converts:
a) Mechanical → Chemical
b) Kinetic → Electrical
c) Potential → Kinetic
d) Sound → Electrical
✅ b) Kinetic → Electrical
Explanation: Moving air turns blades to generate electricity.

What kind of energy is stored in petrol?
a) Thermal
b) Kinetic
c) Chemical
d) Electrical
✅ c) Chemical
Explanation: Hydrocarbon bonds release energy upon combustion.

A battery converts:
a) Light → Chemical
b) Chemical → Electrical
c) Electrical → Mechanical
d) Thermal → Electrical
✅ b) Chemical → Electrical
Explanation: Electrochemical reactions release electrons.

Which device converts heat directly into electricity?
a) Battery
b) Solar cell
c) Thermocouple
d) Generator
✅ c) Thermocouple
Explanation: Two dissimilar metals produce voltage when heated.

What is the energy conversion in a speaker?
a) Electrical → Sound
b) Sound → Electrical
c) Magnetic → Thermal
d) Mechanical → Electrical
✅ a) Electrical → Sound
Explanation: Alternating current causes diaphragm to vibrate and produce sound.

In a coal power plant, energy conversion is:
a) Heat → Mechanical → Electrical
b) Light → Electrical
c) Mechanical → Thermal
d) Chemical → Light
✅ a) Heat → Mechanical → Electrical
Explanation: Coal burns → steam spins turbine → generator produces electricity.

A dam stores which form of energy?
a) Heat
b) Kinetic
c) Potential
d) Sound
✅ c) Potential
Explanation: Water stored at height has gravitational potential energy.

The kinetic energy of a moving object depends on:
a) Height
b) Mass and velocity
c) Surface area
d) Temperature
✅ b) Mass and velocity
Explanation: KE = ½mv².

Which form of energy travels as waves?
a) Kinetic
b) Heat
c) Sound and Light
d) Chemical
✅ c) Sound and Light
Explanation: Sound = mechanical waves; Light = electromagnetic waves.

The energy of a falling object converts from:
a) Potential to kinetic
b) Kinetic to sound
c) Heat to chemical
d) Electrical to mechanical
✅ a) Potential to kinetic
Explanation: Height → motion due to gravity.

Which of these is not a renewable energy source?
a) Solar
b) Coal
c) Wind
d) Biomass
✅ b) Coal
Explanation: Coal is finite and forms over millions of years.

In nuclear power plants, energy comes from:
a) Fission
b) Fusion
c) Combustion
d) Decomposition
✅ a) Fission
Explanation: Splitting of heavy nuclei like uranium releases energy.

In photosynthesis, the radiant energy is stored in:
a) Protein
b) Carbohydrates
c) Fats
d) Minerals
✅ b) Carbohydrates
Explanation: Glucose is formed, which stores energy in bonds.

A refrigerator converts:
a) Heat → Mechanical
b) Electrical → Cooling
c) Chemical → Electrical
d) Electrical → Chemical
✅ b) Electrical → Cooling
Explanation: Uses electric energy to operate a compressor for cooling.

The energy in compressed spring is:
a) Kinetic
b) Thermal
c) Chemical
d) Elastic potential
✅ d) Elastic potential
Explanation: Stored due to shape deformation.

In a solar cooker, energy transformation is:
a) Light → Chemical
b) Light → Heat
c) Heat → Mechanical
d) Electrical → Heat
✅ b) Light → Heat
Explanation: Sunlight is concentrated to produce heat.

Geothermal energy converts:
a) Chemical → Mechanical
b) Heat from Earth → Electrical
c) Electrical → Mechanical
d) Mechanical → Thermal
✅ b) Heat from Earth → Electrical
Explanation: Earth’s heat generates steam to drive turbines.

The mechanical energy is:
a) Kinetic only
b) Potential only
c) Kinetic + Potential
d) Electrical
✅ c) Kinetic + Potential
Explanation: Sum of movement and position-based energy.

What energy transformation occurs in digestion?
a) Mechanical → Heat
b) Chemical → Mechanical
c) Chemical → Heat + Mechanical
d) Electrical → Chemical
✅ c) Chemical → Heat + Mechanical
Explanation: Food energy powers muscles and warms the body.

What is transformed in a candle burning?
a) Chemical → Light + Heat
b) Mechanical → Chemical
c) Electrical → Light
d) Thermal → Sound
✅ a) Chemical → Light + Heat
Explanation: Combustion of wax releases energy.

Wind-up toy converts:
a) Kinetic → Potential
b) Mechanical → Heat
c) Potential → Kinetic
d) Electrical → Mechanical
✅ c) Potential → Kinetic
Explanation: Coiled spring releases stored energy as motion.

An electric bell converts:
a) Mechanical → Sound
b) Electrical → Sound
c) Sound → Mechanical
d) Heat → Sound
✅ b) Electrical → Sound
Explanation: Circuit completes → hammer strikes → produces sound.

Burning of fuel involves:
a) Chemical → Heat
b) Mechanical → Chemical
c) Thermal → Electrical
d) Magnetic → Electrical
✅ a) Chemical → Heat
Explanation: Combustion reaction liberates heat energy.

What is the energy transformation in a hand pump?
a) Heat → Mechanical
b) Mechanical → Potential
c) Chemical → Heat
d) Electrical → Chemical
✅ b) Mechanical → Potential
Explanation: Lifting water raises its gravitational potential.

An LED bulb transforms:
a) Electrical → Light
b) Light → Electrical
c) Mechanical → Electrical
d) Heat → Electrical
✅ a) Electrical → Light
Explanation: Current excites electrons → emits photons (light).

Electric generator converts:
a) Mechanical → Electrical
b) Electrical → Mechanical
c) Chemical → Electrical
d) Electrical → Light
✅ a) Mechanical → Electrical
Explanation: Turbine rotation induces current.

Hydropower involves conversion of:
a) Kinetic → Potential
b) Kinetic → Mechanical → Electrical
c) Thermal → Electrical
d) Sound → Electrical
✅ b) Kinetic → Mechanical → Electrical
Explanation: Flowing water spins turbine → electricity.

Which device converts chemical to electrical energy?
a) Dynamo
b) Battery
c) Solar panel
d) Generator
✅ b) Battery
Explanation: Electrochemical reactions release electrons.

The stored energy in fossil fuels is:
a) Electrical
b) Mechanical
c) Chemical
d) Kinetic
✅ c) Chemical
Explanation: Derived from ancient biological matter.

Radioactive decay releases:
a) Chemical energy
b) Nuclear energy
c) Heat only
d) Light only
✅ b) Nuclear energy
Explanation: Decay of nuclei releases high-energy particles.

Energy in a moving vehicle is:
a) Chemical
b) Heat
c) Potential
d) Kinetic
✅ d) Kinetic
Explanation: Due to motion.

Which device uses chemical → electrical → mechanical energy?
a) Speaker
b) Torch
c) Electric car
d) Solar heater
✅ c) Electric car
Explanation: Battery supplies electricity to motors.

Biomass energy converts:
a) Chemical → Heat
b) Electrical → Heat
c) Light → Chemical
d) Mechanical → Light
✅ a) Chemical → Heat
Explanation: Biomass burns or decomposes to produce heat.

Energy in muscles is:
a) Thermal
b) Kinetic
c) Chemical
d) Electrical
✅ c) Chemical
Explanation: ATP molecules store usable chemical energy.

Lightning shows which energy change?
a) Chemical → Electrical
b) Mechanical → Light
c) Electrical → Light + Sound
d) Thermal → Electrical
✅ c) Electrical → Light + Sound
Explanation: High voltage discharges as light and thunder.

In a pendulum, energy continuously shifts between:
a) Electrical and mechanical
b) Potential and kinetic
c) Thermal and mechanical
d) Chemical and sound
✅ b) Potential and kinetic
Explanation: At top = potential, at lowest = kinetic.

In a firecracker, energy transformation is:
a) Chemical → Light + Sound + Heat
b) Mechanical → Thermal
c) Thermal → Electrical
d) Sound → Mechanical
✅ a) Chemical → Light + Sound + Heat
Explanation: Rapid combustion releases multiple energy forms.