Most Repeated MDCAT Physics: Current Electricity MCQs

Explanation

Explanation:Total resistance (R) = internal resistance (r) + heater resistance (R_heater) = 1.5 Ω + 6.5 Ω = 8 Ω. Current (I) = emf (ε) / R = 20 V / 8 Ω = 2.5 A. Power (P) = I²R_heater = (2.5 A)² × 6.5 Ω = 40.625 W ≈ 41 W.

Explanation

Kirchhoff's first law states that the algebraic sum of current flowing into a junction is zero. This rule corresponds to conservation of charge which states that total charge in a closed system remains constant because current is the rate of flow of charge.

Explanation

The fractional change in resistance per kelvin is called the temperature coefficient.The temperature coefficient of resistance is a measure of how much the electrical resistance of a material changes with temperature. It is expressed in units of ohms per ohm per degree Celsius (Ω/Ω/°C) or ohms per ohm per kelvin (Ω/Ω/K). This coefficient is denoted by the symbol α (alpha) and is an important factor in understanding and designing electronic circuits, particularly when dealing with components like resistors whose resistance can vary with temperatureResistance coefficient, abbreviated as K, a dimensionless number, is how much resistance to the flow an obstacle has.

Explanation

Conductance is the reciprocal of resistance. It is a measure of how easily an electrical current can pass through a material. The unit of conductance is the Siemens (S) or Mho, which is the inverse of the Ohm. Therefore, option d is correct.

Explanation

"The current flowing through a conductor is directly proportional to potential difference across its ends provided the physical state such as temperature etc. remains constant." Hence, option D is correct.

Explanation

The correct answer is terminal voltage, which specifically refers to the voltage across the terminals of a battery when it is connected to a load. This voltage is affected by the internal resistance of the battery and can be lower than the EMF of the battery when a current flows. Potential difference refers to the general concept of voltage difference but does not specify the context of a battery's terminals under load. EMF is the maximum voltage the battery can provide when no current is drawn; it does not account for the effects of internal resistance. Internal potential energy is more about the stored energy inside the battery rather than the voltage available at its terminals.

Explanation

Conductivity is the measure of a material's ability to conduct electric current. It is the reciprocal of resistivity.

Explanation

According to Faraday's law of electromagnetic induction, the magnitude of the induced electromotive force (emf) and hence the current produced in a coil depends on the rate of change of magnetic flux through the coil. This rate of change of magnetic flux depends on factors such as the strength of the magnetic field, the area of the coil, and the rate of rotation or change in orientation of the coil with respect to the magnetic field.

Explanation

When two metallic conductors have the same value of resistivity, we can differentiate them based on their temperature coefficient. The temperature coefficient of a conductor tells us how its resistance changes with temperature. Different metals have different temperature coefficients, which means their resistance will change at different rates as the temperature changes. By comparing the temperature coefficients of the two conductors, we can determine how their resistances will vary with temperature.

Explanation

When three equivalent resistors are connected in parallel, the equivalent resistance is 3/R. When these same resistors are connected in series, their resistances add up, resulting in an equivalent resistance of 3R. Therefore, the correct option is 3R. Options B, C, and D are incorrect because they do not align with the calculations for equivalent resistance in parallel and series resistor connections.