CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Convection
Sea breezes are an example of what heat-transfer process?
A. Refraction
B. Nuclear fission
C. Convection
D. Conduction only
Correct Answer: C
Unequal heating of land and sea drives convective air circulation.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Convection
What is a convection current?
A. Circulating fluid motion driven by temperature and density differences
B. An electric current only
C. A light ray
D. A chemical bond
Correct Answer: A
Rising warm fluid and sinking cool fluid can form circulation cells.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Convection
In which materials does convection occur most readily?
A. Metals only
B. Rigid solids only
C. Liquids and gases
D. Vacuum only
Correct Answer: C
Convection requires bulk fluid flow.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Convection
What causes natural convection?
A. Sound waves
B. Magnetic fields only
C. Radioactivity
D. Density differences produced by temperature differences
Correct Answer: D
Warmer fluid often becomes less dense and rises while cooler fluid sinks.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Convection
What is convection?
A. Heat transfer only by radiation
B. No energy transfer
C. Heat transfer only through solids
D. Heat transfer by bulk motion of a fluid
Correct Answer: D
Convection occurs in liquids and gases through fluid motion.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Conduction
Does conduction require a material medium?
A. No, it works through vacuum most effectively
B. Only for sound
C. Yes
D. Only for light
Correct Answer: C
Conduction depends on interactions within matter.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Conduction
Why do metals conduct heat well?
A. They contain no atoms
B. They always melt
C. Free electrons can transfer energy rapidly through the metal
D. They have no resistance to anything
Correct Answer: C
Electron transport supplements lattice vibration in metals.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Conduction
Which material is a thermal insulator?
A. Silver
B. Copper
C. Styrofoam
D. Aluminum
Correct Answer: C
Styrofoam contains trapped air and has low thermal conductivity.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Conduction
Which material is a good thermal conductor?
A. Copper
B. Wood
C. Air
D. Plastic
Correct Answer: A
Copper transfers thermal energy efficiently.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Conduction
In which state is conduction typically most effective?
A. Gases only
B. Empty space
C. Solids
D. Vacuum
Correct Answer: C
Closely packed particles and, in metals, free electrons make conduction effective in solids.
CSS - PMS - CCE - PCS - General Science
Heat & Thermodynamics - Conduction
What is thermal conduction?
A. Creation of heat from nothing
B. Heat transfer by bulk fluid motion
C. Transfer of heat through a material without bulk movement of the material
D. Heat transfer only by electromagnetic waves
Correct Answer: C
Conduction transfers energy through particle interactions and, in metals, mobile electrons.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Voltage
A 9 V battery provides approximately how much energy per coulomb of charge?
A. 9 joules
B. 1 joule
C. 81 joules
D. 0 joule
Correct Answer: A
Since 1 volt = 1 joule per coulomb, 9 V corresponds to 9 J/C.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Voltage
How is a voltmeter connected in a circuit?
A. Between no points
B. In parallel across the component
C. In series only
D. Directly shorted across the battery with zero resistance
Correct Answer: B
A voltmeter measures the difference in potential between two points.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Voltage
What instrument measures potential difference?
A. Voltmeter
B. Thermometer
C. Ammeter
D. Ohmmeter only
Correct Answer: A
A voltmeter is connected across two points.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Voltage
Which equation relates voltage V, energy W and charge Q?
A. V = W/Q
B. V = IR² only
C. V = m/g
D. V = Q/W
Correct Answer: A
One volt equals one joule per coulomb.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Voltage
What is the SI unit of voltage?
A. Watt
B. Ampere
C. Volt
D. Ohm
Correct Answer: C
Potential difference is measured in volts.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Voltage
What is voltage?
A. Force per unit mass
B. Resistance only
C. Rate of charge flow
D. Electric potential difference, or energy transferred per unit charge
Correct Answer: D
Voltage measures potential-energy change per coulomb of charge.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
Why are transformers important in power transmission?
A. They stop electric fields
B. They generate fuel
C. They eliminate all losses completely
D. High-voltage transmission can reduce current and resistive losses for a given power
Correct Answer: D
Stepping voltage up lowers current, reducing I²R line losses.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
For an ideal transformer, Vp/Vs equals what ratio?
A. Np/Ns
B. fp/fs
C. Is/Ip only in the same direction
D. Rp/Rs always
Correct Answer: A
Voltage ratio equals turns ratio for an ideal transformer.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Transformers
Why do ordinary transformers require alternating current?
A. Transformers need no magnetic field
B. AC contains no electrons
C. DC has too much frequency
D. A changing current produces changing magnetic flux needed for induction
Correct Answer: D
Constant DC does not continuously induce emf in the secondary after transients die out.