Q. A liquid drop is formed on a surface. The angle formed between the tangent to the drop surface and the solid surface is called what?
A.Contact angle
B.Surface angle
C.Tension angle
D.Cohesion angle
Solution
The angle formed between the tangent to the drop surface and the solid surface is known as the contact angle, which indicates the wettability of the surface.
Q. A loop of wire is moved into a magnetic field at a constant speed. What is the effect on the induced current as the loop enters the field?
A.It increases
B.It decreases
C.It remains constant
D.It becomes zero
Solution
As the loop enters the magnetic field, the area of the loop within the field increases, leading to an increase in magnetic flux and thus an increase in the induced current according to Faraday's law.
Q. A loop of wire is placed in a uniform magnetic field. If the angle between the field and the normal to the loop is 60 degrees, what is the effective magnetic flux?
A.0.5 B A
B.0.866 B A
C.0.866 B A²
D.B A
Solution
Effective magnetic flux (Φ) = B * A * cos(θ) = B * A * cos(60°) = 0.5 B A.
Q. A loop of wire is placed in a uniform magnetic field. What happens if the magnetic field strength is increased?
A.Induced current flows in the loop
B.No effect on the loop
C.The loop will heat up
D.The loop will move
Solution
According to Faraday's law of electromagnetic induction, a change in magnetic field strength induces an electromotive force (EMF) in the loop, causing a current to flow.
Correct Answer: A — Induced current flows in the loop
Q. A loop of wire is placed in a uniform magnetic field. What happens to the induced EMF if the area of the loop is increased?
A.Increases
B.Decreases
C.Remains the same
D.Depends on the magnetic field strength
Solution
According to Faraday's law of electromagnetic induction, the induced EMF is directly proportional to the rate of change of magnetic flux, which increases with an increase in the area of the loop.
Q. A man is standing 100 meters away from a building. If the angle of elevation to the top of the building is 45 degrees, what is the height of the building?
A.100 m
B.50 m
C.75 m
D.25 m
Solution
Using tan(45°) = height/distance, we have height = distance * tan(45°) = 100 * 1 = 100 m.
Q. A man is standing 30 meters away from a tower. If the angle of elevation of the top of the tower from the man's position is 30 degrees, what is the height of the tower?
Q. A man is standing 30 meters away from a tree. If the angle of elevation from his eyes to the top of the tree is 30 degrees, what is the height of the tree?
Q. A man is standing 30 meters away from a tree. If the angle of elevation of the top of the tree from his eyes is 60 degrees, what is the height of the tree?
