The voltage of the domestic electric supply is represented by the equation V = 311 sin314.2t. Determine the frequency of the a.c. supply [\(\pi\) = 3.142]

• A. 50.0Hz
• B. 100.0Hz
• C. 311.0Hz
• D. 314.2Hz

Convex mirrors are used as driving mirrors because images formed are

• A. erect, Virtual and diminished
• B. erect, real and diminished
• C. erect, virtual and magnified
• D. inverted, virtual and diminished

How many grams of water at 17^oC must be added to 42g of ice at 0^oC to melt the ice completely? [specific latent heat of fusion of ice = 3.4 x 10⁵Jkg^-1, specific heat capacity of water = 4200Jkg^-1k^-1]

• A. 200g
• B. 300g
• C. 320g
• D. 400g

If a resistance is halved in value and the potential difference across it is tripled, then the ratio of the new current to the old one is

• A. 1 : 6
• B. 1 : 3
• C. 2 : 1
• D. 6 : 1

n homes, electrical appliances and lamps are connected in parallel because

• A. less current will be used
• B. less voltage will be used
• C. parallel connection does not heat up the wires
• D. series connection uses high voltage

a pilot records the atmospheric pressure outside his plane as 63cm of Hg while a ground observer records a reading of 75cm of Hg with his barometer. Assuming that the density of air is constant, calculate the height of the plane above the ground. (take the relative densities of air and mecury as 0.00136 and 13.6 respectively)

• A. 120m
• B. 138m
• C. 274m
• D. 1200m

When an air column is set into vibrations, the distance between two consecutive nodes of the resultant wave is

• A. one quarter of the wavelength
• B. half of the wavelength
• C. the wavelength
• D. twice the wavelength

Which of the arrangements of radiations below shows decreasing order of wavelengths?

• A. X-rays> radio waves > infrared radiations
• B. Radio waves> infrared radiations > X-rays
• C. Infrared radiations > radio waves > X-rays
• D. X-rays> infrared radiations > radio waves

An object moves in a circular path of radius 0.5m with a speed of 1m/s What is its angular velocity?

• A. 8 rad/s
• B. 4 rad/s
• C. 2 rad/s
• D. 1 rad/s

A pool of water appears to be 1.00m deep when viewed vertically from above. What is the actual depth of the pool? [Refractive index of water = 1.33]

• A. 13.300m
• B. 0.750m
• C. 1.013m
• D. 1.330m