Electricity & Magnetism
True/False
A voltmeter must be connected in series to measure voltage across a resistor.
False
A voltmeter is connected in parallel across components to measure potential difference. If connected in series, it would alter the circuit and give incorrect readings.
Fill in the Blanks
The magnetic field around a straight current-carrying wire forms ___ concentric circles.
A. clockwise
B. anticlockwise
C. alternating
D. circular
D. circular
Magnetic field lines form circular loops around the wire, direction given by the right-hand rule.
MCQ
Which process involves energy transfer without movement of particles?
A. Conduction
B. Convection
C. Radiation
D. Evaporation
C. Radiation
Radiation transfers energy via electromagnetic waves, requiring no medium ā unlike conduction and convection.
True/False
Solids have fixed volume but variable shape.
False
Solids have both fixed volume and fixed shape due to tightly packed particles in a rigid structure. Liquids have fixed volume but variable shape.
True/False
Energy can be created and destroyed in a closed system.
False
According to the Law of Conservation of Energy, energy cannot be created or destroyed ā only transformed from one form to another.
MCQ
Which of the following increases the resistance of a wire?
A. Shorter length
B. Larger cross-section
C. Higher temperature
D. Lower resistivity
C. Higher temperature
As temperature increases, atoms vibrate more, impeding electron flow ā hence resistance increases.
True/False
A transformer works with direct current (DC).
False
Transformers require alternating current (AC) to induce changing magnetic fields for voltage transformation. DC produces a constant field, so no induction occurs.
True/False
Boiling and evaporation occur at the same temperature.
False
Boiling occurs at a fixed temperature (boiling point), while evaporation happens at any temperature below boiling, from the surface only.
MCQ
Which of the following best explains why gases are compressible?
A. They have low mass
B. Their particles are in fixed positions
C. Their particles are far apart
D. They have high density
C. Their particles are far apart
Gas particles are widely spaced, allowing them to be compressed easily. In contrast, solids and liquids have closely packed particles.
MCQ
A 100 W bulb is used for 5 hours. How much energy is consumed?
A. 500 J
B. 500 W
C. 500 Wh
D. 20 kWh
C. 500 Wh
Energy = Power Ć Time = 100 W Ć 5 h = 500 Wh. Convert to kWh if needed for billing.
Fill in the Blanks
The current in a conductor is directly proportional to the ___ across it, provided temperature remains constant.
A. voltage
B. resistance
C. power
D. charge
A. voltage
This is Ohmās Law: IāV when temperature is constant.
MCQ
Which of the following best explains why metals conduct electricity?
A. They have loosely bound protons
B. Their atoms are tightly packed
C. They contain free electrons
D. They have high melting points
C. They contain free electrons
Metals have delocalized electrons that move freely, allowing current to flow.
MCQ
Which of the following best explains why metal feels colder than wood at room temperature?
A. Metal has lower specific heat capacity
B. Metal is a better conductor
C. Metal has higher density
D. Metal reflects heat
B. Metal is a better conductor
Metal conducts heat away from your skin faster than wood, making it feel colder even though both are at the same temperature.
Fill in the Blanks
The state of matter with the weakest intermolecular forces is the ___ state.
A. gaseous
B. solid
C. liquid
D. plasma
A. gaseous
Gases have the weakest intermolecular forces, allowing particles to move freely and occupy any volume.
True/False
A heavier object always has more kinetic energy than a lighter one.
False
Kinetic energy depends on both mass and velocity: KE=1/2mv2. A lighter object moving faster can have more KE than a heavier one moving slowly.
True/False
In a parallel circuit, the total resistance is greater than the largest individual resistor.
False
In parallel, total resistance is less than the smallest resistor. This is because current has multiple paths.
Fill in the Blanks
The unit of electrical energy used in households is the kilowatt-___.
A. hour
B. second
C. volt
D. ampere
A. hour
Kilowatt-hour (kWh) is the energy consumed when 1 kW is used for 1 hour.
Fill in the Blanks
The specific heat capacity of a substance is the amount of heat required to raise the temperature of ___ kg by 1Ā°C.
A. 1
B. 10
C. 100
D. 0.1
A. 1
Specific heat capacity is defined per 1 kg of substance per degree Celsius.
MCQ
Which of the following changes involves a chemical change?
A. Melting ice
B. Boiling water
C. Rusting iron
D. Condensing steam
C. Rusting iron
Rusting is a chemical reaction between iron and oxygen, forming a new substance (iron oxide). The others are physical changes.
Fill in the Blanks
The energy stored in a compressed spring is called ___ energy.
A. elastic
B. kinetic
C. thermal
D. nuclear
A. elastic
Elastic potential energy is stored when an object is stretched or compressed.
MCQ
A 60 W bulb and a 100 W bulb are connected in series. Which glows brighter?
A. 60 W
B. 100 W
C. Both equally
D. Neither glows
A. 60 W
In series, both bulbs get the same current. The bulb with higher resistance (lower wattage) dissipates more energy per unit time and glows brighter.
MCQ
What happens to the current if voltage is doubled and resistance remains constant?
A. Doubles
B. Halves
C. Stays the same
D. Quadruples
A. Doubles
From Ohmās Law: I=V/R. If V doubles and R is constant, current also doubles.
True/False
Latent heat causes a temperature change during phase transitions.
False
Latent heat is absorbed or released without changing temperature ā itās used to break or form intermolecular bonds during phase changes.
MCQ
Which statement best describes the particles in a liquid?
A. Fixed positions
B. Free to move in all directions
C. Closely packed but able to slide past each other
D. Widely spaced and moving randomly
C. Closely packed but able to slide past each other
Liquid particles are close together but not fixed ā they can slide past each other, giving liquids fluidity but fixed volume.
MCQ
Which of the following devices converts chemical energy into electrical energy?
A. Solar panel
B. Battery
C. Generator
D. Motor
B. Battery
A battery uses chemical reactions to produce electrical energy.