Physics MCQ Quiz - Scalar Quantities
Explanation:
The correct answer is Work and Current.
Work is a scalar quantity because it's the dot product of force and displacement (both vectors), and dot product always yields a scalar. Current is a scalar as it's defined by charge flow per unit time, regardless of direction.
The other options are incorrect because:
- Force and Angular Momentum: Both are vector quantities with direction
- Electric Field and Magnetic Moment: Both are vector quantities
- Linear Momentum and Average Velocity: Both are vector quantities
Explanation:
The correct answer is Work.
Work is always a scalar quantity because it's defined as the dot product of force and displacement vectors, which results in a scalar value. It has magnitude but no direction.
The other options are incorrect because:
- Displacement: Vector quantity (has direction)
- Velocity: Vector quantity (speed with direction)
- Torque: Vector quantity (cross product of force and distance)
Explanation:
The correct answer is A scalar quantity.
The dot product (or scalar product) of two vectors always yields a scalar quantity. It's calculated as the product of the magnitudes of the two vectors and the cosine of the angle between them, which is a scalar value.
The other options are incorrect because:
- A vector quantity: This describes the result of a cross product, not dot product
- A tensor quantity: Dot product doesn't result in a tensor
- Another vector perpendicular to both: This describes the cross product result
Explanation:
The correct answer is Force.
Force is different because it's a vector quantity (has both magnitude and direction), while the other three (Pressure, Energy, and Power) are scalar quantities that can be completely described by their magnitude alone.
The other options are incorrect because:
- Pressure: Scalar (force per unit area, no direction)
- Energy: Scalar (capacity to do work)
- Power: Scalar (rate of doing work)
Explanation:
The correct answer is It's described only by magnitude without direction.
Current is a scalar quantity because it's completely described by its magnitude (charge flow per unit time). Although current has an associated direction of charge flow, the quantity itself doesn't have directional properties that affect its behavior in calculations.
The other options are incorrect because:
- It follows Ohm's Law: Many vector quantities follow laws but remain vectors
- It's the ratio of two scalar quantities: Current is charge/time, and charge is scalar, but this isn't the defining reason
- It's always positive: Current can be negative (direction reversal), but still scalar
