Physics Test 286

Result

Physics Test 286

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Weekly Quiz Competition

Question 1
4 / -1

If E and B represent electric and magnetic field vectors of an electromagnetic wave, the direction of propagation of the wave is along

A

B

C

D

Solution
Question 2
4 / -1

A body of mass 10kg is moving on a horizontal surface by applying a force of 10 N in the forward direction. The body moves with a constant velocity of 0.2 ms^-1.

Work done by the force of friction in the first 10 seconds is

A
-20 J

B
10 J

C
20 J

D
-5 J

Solution
Question 3
4 / -1

A

B

C

D

Solution

Formula for electric field (magnitude) in a medium:
Question 4
4 / -1

A

B

C

D

Solution
Question 5
4 / -1

The steradian (sr) is the SI unit for:

A
Plane angle

B
Solid angle

C
Luminous intensity

D
Electric current

Solution

Step 1: Understand the question.
The question asks for the physical quantity that the SI unit "steradian" (sr) measures. Step 2: Recall the definition of steradian.
A steradian is defined as the solid angle that, having its vertex at the center of a sphere, cuts off an area on the surface of the sphere equal to the area of a square with sides of length equal to the radius of the sphere. Step 3: Relate the definition to the concept of angle.
While the radian (rad) measures a plane angle (2-D angle), the steradian (sr) measures a solid angle (3-D angle). Solid angle is the 3-D equivalent of plane angle, subtended by a surface at a point. Step 4: Eliminate incorrect options.
A) Plane angle → measured in radians, not steradians.
C) Luminous intensity → measured in candela (cd).
D) Electric current → measured in ampere (A). Step 5: Conclude.
Therefore, the steradian is the SI unit for solid angle.
Question 6
4 / -1

What is the mathematical expression for instantaneous velocity?

A

B

C

D

Solution

Instantaneous velocity is defined as the limit of average velocity as the time interval approaches zero, which is the derivative of position with respect to time,
Question 7
4 / -1

The unit of magnetic field tesla (T) is equivalent to:

A

B

C

D
All of the above

Solution
Question 8
4 / -1

A

B

C
m= τ B sinθ

D
τ = m B cosθ

Solution
Question 9
4 / -1

If the distance between two point charges is halved, the electrostatic force between them becomes:

A
Double

B
Four times

C
Half

D
One-fourth

Solution
Question 10
4 / -1

A parallel plate capacitor of capacitance C is charged to a potential difference V. The battery is then disconnected, and a dielectric slab of dielectric constant K is inserted fully between the plates.

Which of the following statements is correct?

A
The potential difference across the plates remains the same, but the charge stored increases

B
The potential difference across the plates decreases, but the charge stored remains the same

C
Both the potential difference and the charge stored decrease

D
Both the potential difference and the charge stored increase

Solution