A metre used to measure the length of a piece of string in a certain experiment. It is found to be 20 cm long to the the nearest millimeter. How should this result be recorded in a table of results?

• 0.2000 m

• 0.200 m

• 20 m

• 0.2 m

An athlete makes a long jump and follows a projectile motion. Air resistance is negligible. Which one of the following statement is true about the athlete?

• The athelete has constant horizontal and vertical velocities

• The athlete has a constant horizontal velocity and constant downward acceleration

• The athelete has a constant upward acceleration followed by a constant downward acceleration

• The athelete has a constant upward velocity followed by a constant downward acceleration

A boy walks towards a stationary plane mirror at a speed of 1.2 ms^-1 . What is the relative speed of approach of the boy and his image?

• zero

• 1.2 ms^-1

• 2.4 ms^-1

• 1.44 ms^-1

The critical angle between an equilateral prism and air is 45°. What happens to the incident ray perpendicular to the refracting surface?

• It is reflected totally from the second surface and emerges perpendicular from the third surface

• It gets reflected reflected from second and third surface and emerges from the first surface

• It keeps reflecting from all three sides of the prism and never emerges out

• After deviation, it gets refracted from the second surface

If the formation of a rainbow, the light from the sun on water droplets undergoes which of the following phenomenon/phenomena

• dispersion only

• only total reflection

• dispersion and total internal reflection

• scattering

In what unit is the power of lens measured?

• watt

• metre

• dioptre

• Hertz

A piece of wire of resistance R is bent through 180° at mid-point and the two halves are twisted together. What is the resistance of the wire thus formed?

• R/4

• R/2

• R

• 2R

What are the elementary particles with half spin called?

• quarks

• bosons

• fermions

• hadrons

What is the vertical component of the force 5N acting on a particle alonga direction making an angle of 60°?

• 3 N

• 2.5 N

• 10 N

• 4 N

NC^-1 has the same dimension as

• Volt meter

• Farad meter

• Frad/meter

• Volt/meter