Light of energy 1.12 x 10\(^{-18}\) J is incident on a metal of ejected electrons with maximum energy of 8.0 x 10\(^{-19}\)J. Calculate the threshold frequency of the metal. [h = 6.626 x 10\(^{-34}\)Js]
- A. 4.8 x 10\(^{14}\)Hz
- B. 1.2 x 10\(^{15}\)Hz
- C. 1.7 x 10\(^{15}\)Hz
- D. 2.8 x 10\(^{15}\)Hz
A body of mass, m is projected vertically upward with a velocity, y. At what position will the potential energy be maximum?
- A. \(\frac{y}{g}\)
- B. \(\frac{2y^2}{g}\)
- C. \(\frac{y^2}{2g}\)
- D. \(\frac{y^2}{4g}\)
A 2 ΞΌF capacitor is connected directly across a 150 V\(_{rms}\), 60 Hz A.C source. Calculate the r m s value of the current.
- A. 0.113 A
- B. 0.160 A
- C. 150 A
- D. 1324 A
A constant voltage source supplies a sinusoidal alternating e.m.f. The voltage marked against the components are their peak values. Determine the peak value of the applied e.m.f
- A. 1V
- B. 4V
- C. 5V
- D. 2V
For a convex lens to form a real image, the distance between the object and the screen will be:
- A. equal to the focal length of the lens
- B. less than the focal length of the lens
- C. twice the focal length of the lens
- D. four times the focal length of the lens
A particle of mass 3.6 x 10\(^{-6}\)kg revolving around the earth has a radial acceleration of 4.3 x 10\(^7\)ms\(^{-2}\). Calculate the centripetal force of the particle.
- A. 1.55 x 10\(^2\)N
- B. 2.00 x 10\(^{-2}\)N
- C. 6.25 x 10\(^{-14}\)N
- D. 1.00 x 10\(^2\)N
In the circuit diagram above, which lamp causes the other to go off?
- A. P
- B. Q
- C. R
- D. S
Two isolated charged spheres each of magnitude + 1.0 x 10\(^{-6}\) C are seperated by a distance of 2.0 x 10\(^{-1}\) m. Calculate the magnitude of the electrostatic force between them [K = \(\frac{1}{4\pi \epsilon_o}\) = 9 x 10\(^9\)Nm\(^2\)C\(^{-2}\)]
- A. 2.25 x 10\(^{-1}\)N
- B. 4.50 x 10\(^{-1}\)N
- C. 2.25 x 10\(^1\)N
- D. 4.50 x 10\(^1\)N
All of the following uses are practical applications of x-ray except
- A. the treatment of tumors
- B. determining the depth of a mine
- C. dental operation
- D. detecting fractures in bones
A temperature of 60ΒΊ C is equivalent to
- A. 25ΒΊF
- B. 140ΒΊF
- C. 50ΒΊF
- D. 108ΒΊF
A cube of water with side 10.0 cm floats vertically in water with 4.5 cm its length submerged. Calculate the density of the wood.
[Density of water = 1 g/cm\(^3\); D = 0.090 g/cm\(^3\)]
- A. 0.090 g/cm\(^3\)
- B. 0.450 g/cm\(^3\)
- C. 0.230 g/cm\(^3\)
- D. 0.0450 g/cm\(^3\)
Chromatic aberration in lenses can be corrected by using a combination of
- A. diverging and converging lenses.
- B. an opaque material to cover the rims of lenses.
- C. wide parallel beams on the lenses' surface.
- D. a thin convex lens.
An object is placed 1.5 m from a plane mirror. How far is the image from the object?
- A. 3.0 m
- B. 1.3 m
- C. 1.0 m
- D. 0.3 m
To convert a milli-ammeter to an ammeter, a resistor of low value is necessary to connect a resistor of
- A. low value in series with it
- B. high value in series with it
- C. low value in parallel with it
- D. high value in parallel with it
A stone of mass 200 g attached to a string is made to revolve in a horizontal circle of radius 1.5 m at a steady speed of 5 m/s. Calculate the tension in the string at the bottom of the circle.
- A. 5.3 N
- B. 3.3 N
- C. 2.0 N
- D. 1.3 N
The law of conservation of momentum is stated for closed and isolated system. What are the two conditions for a system to be closed and isolated?
- A. No external force acts on the system and there is no change in mass of the system.
- B. No external force acts on the system and there is a gain in mass.
- C. No external force acts on the system and there is a loss in mass.
- D. An external force acts on the system and there is no change in mass.
A body moves with uniform velocity when the resultant force on it is
- A. greater than the frictional force acting on it
- B. less than the frictional force acting on it
- C. equal to zero
- D. equal to unity
The function of a fuse in an electric circuit is to
- A. break the circuit when the current exceeds a certain value
- B. save energy by reducing voltage
- C. ensure that the current in the circuit exceeds a certain value
- D. save energy by reducing the current
A ray of light travels from a less dense medium to a denser medium. How are the speed and frequency of the light affected? The speed
- A. Increases and the frequency increases
- B. decreases and the frequency decreases
- C. increases and the frequency remains the same
- D. decreases and the frequency remains the same
The diagram above illustrates the motion of a cyclist from P to R. The distance travelled is determined by the
- A. area under QR
- B. gradient of QR
- C. area under PQR
- D. gradient of PQR
The capacitance of a parallel plate capacitor
- A. decreases when the temperature between the plates decreases
- B. increases when the potential difference between the plates is increased
- C. is greater without a dielectric between the plates than with dielectric
- D. is greater with dielectric between the plates than without dielectric.