A metal with a work function of 3.0ev is irradiated with ultraviolet light of energy 4.0 ev. The kinetic energy of the ejected electron is
- A. 1.0eV
- B. 3.0eV
- C. 4.0eV
- D. 7.0eV
An atom in an excited state is one whose
- A. potential energy is minimum
- B. potential energy is maximum
- C. electron are in the conduction band
- D. electron have moved to higher energy level
In a R-C circuit
- A. Irms leads Vrms by 60o
- B. Irms slags Vrms by 60o
- C. Vrms lags Irms by 90o
- D. Vrms leads Irms by 90o
An inductor is connected to a 24V, 50Hz mains supply. If the current through the inductor is 1.5A, calculate the inductance of the inductor (\(\pi = \frac{22}{7}\))
- A. 8.0 x 102H
- B. 7.5 x 10oH
- C. 1.6 x 10oH
- D. 5.1 x 10-2H
Which of the following modes is the most economical method of transmitting electrical power over long distances?
- A. alternating current at low voltage and high current
- B. alternating current at high voltage and high current
- C. alternating current at high voltage and low current
- D. direct current at low voltage and high current
the core of a transformer is usually laminated in order to
- A. reduce magnetic leakage
- B. reduce eddy current
- C. prevent vibration of the transformer
- D. make magnetic reversal in the core much easier
The magnetic relay is a device used for
- A. timing in sports
- B. storing magnetic field
- C. readin the magnitude of magnetic flux
- D. controlling another circuit carrying larger current
A 12\(\Omega\) resistor dissipates 8kJ of heat in 20s. Calculate the current through the resistor
- A. 5.8A
- B. 6.9A
- C. 30.0A
- D. 33.3A
Two similar cells are used to light two similar lamps as illustrated in the diagrams above. In which of the circuit diagrams are the lamps brightest?
- A. P
- B. Q
- C. R
- D. S
Six dry cells each of e.m.f. 2.0 and internal resistance of 1.0\(\Omega\) are connected in parallel across a load of 3.0\(\Omega\). Calculate the effective current in the circuit.
- A. 0.63A
- B. 0.50A
- C. 0.31A
- D. 0.22A
Which of the following properties is an advantage of lead-acid accumulator over an alkaline accumulator?
- A. possesses low internal resistance
- B. can be recharges
- C. has shorter life span
- D. possesses high e.m.f
Two capacitors, each of capacitance 2\(\mu\)F are connected in parallel. If the p.d across them is 120V, calculate the charge on each capacitor
- A. 6.0 x 10-5C
- B. 1.2 x 10-4C
- C. 2.4 x 10-4C
- D. 4.8 x 10-4C
When two like charges are brought together, the potential energy of the system formed will
- A. increase because work is done against the field
- B. increase because work is done by the field
- C. decrease because work is done by the field
- D. decrease because work is done against the field
Which of the following sets of coloured light is/are secondary colours i. Red, Blue and green ii. Blue, cyan and magneta iii. Green, Magenta and yellow, IV Yellow, Cyan and Magenta
- A. i and ii only
- B. ii and iii only
- C. iv only
- D. i, ii and iv only
The sound heard by a person after the reflection of the sound generated by him is called
- A. reverberation
- B. resonance
- C. echo
- D. audibility
A telescope is said to be in normal adjustment when the
- A. focal length of he objective is greater than that of the eyepiece
- B. focal length of the eyepiece is greater than that of the objective
- C. focal length of the eyepiece is equal to that of the objective
- D. objective focal point coincides wih that of the eyepiece
An object is placed 10cm from a converging lens of foal length 15cm. Calculate the magnification of the image formed
- A. 3.0
- B. 1.5
- C. 0.6
- D. 0.3
An object is placed at a point X between the focal point F and the optical centre C of a diverging lens. If F is the focal point on the other side of the lens, the image of the object is formed between
- A. F and X
- B. X and C
- C. C and F
- D. F and 2F
A ray of light passes from air to water to glass to air. Given that the refractive index for light passing from air to water is \(\frac{4}{3}\) and air to glass is \(\frac{3}{2}\), calculate the refractive index of glass relative to water
- A. 0.50
- B. 0.67
- C. 0.75
- D. 1.13
An object of height 2.5cm is places 20cm from a convex mirror of focal length 10cm. Calculate the height of its image.
- A. 2.5 cm
- B. 3.0cm
- C. 5.0cm
- D. 25.0cm
Which of the following properties of waves is exclusive to transverse waves?
- A. reflection
- B. interference
- C. diffraction
- D. polarization