A device consumes 100 W of power when connected to a 120 V source. Calculate its resistance.
- A. 1.2\(\Omega\)
- B. 12,000 \(\Omega\)
- C. 20.0\(\Omega\)
- D. 144\(\Omega\)
An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius
6.1 x 10\(^{11}\) m. Calculate the centripetal force acting on the electron.
- A. 7.7 x 10\(^{47}\) N
- B. 6.0 x 10\(^{-8}\)N
- C. 3.0 x 10\(^{-14}\)N
- D. 1.3 x 10\(^{-26}\)N
An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius 6.1 x 10(^{11}\) m. Determine the angular speed of the electron.
- A. 3.28 x 10\(^{16}\) rad s\(^{-1}\)
- B. 8.55 x 10\(^{3}\) rad s\(^{-1}\)
- C. 9.11 x 10\(^{13}\) rad s\(^{-1}\)
- D. 5.22 x 10\(^{15}\) rad s\(^{-1}\)
Which of the following devices is used for storing electric charges?
- A. Transformer
- B. Ammeter
- C. Potentiometer
- D. Capacitor
The diagram above illustrates a meter bridge circuit underbalanced conditions. Determine the value of x.
- A. 50.cm
- B. 10.0 cm
- C. 28.6 cm
- D. 57.2 cm
Which of the following statements is the correct reason for using soft iron in making the armature or an electric bell?
- A. It is a diamagnetic material
- B. It loses its magnetism readily
- C. It is not easily magnetized
- D. It retains its magnetism for a long time
An a.c. the generator can be converted to a d.c. generator by replacing the
- A. commutator with an armature
- B. armature with a commutator
- C. commutator with slip rings
- D. slip rings with a commutator
The maximum and minimum thermometer reads the
- A. the maximum temperature during the day and the minimum temperature at night at all times.
- B. the maximum temperature at night and minimum temperature during the day from the last reset
- C. the maximum temperature at night and minimum temperature during the day at all times
- D. the maximum temperature during the day and minimum temperature at night from the last reset
The mass of a load is doubled while the force acting on it is halved. The resulting acceleration of the load is
- A. quadrupled
- B. quartered
- C. halved
- D. doubled
An 800 kg car moving at 80 km hr\(^{-1}\) collides with a 1200 kg car moving at 40 km hr\(^{-1}\) in the same direction. If the cars stick together, calculate their common velocity.
- A. 60 km hr\(^{-1}\)
- B. 8 km hr\(^{-1}\)
- C. 40 km hr\(^{-1}\)
- D. 56 km hr\(^{-1}\)
Which of the following graphs gives the correct relationship between energy and mass when mass is converted to energy.
- A. A
- B. B
- C. C
- D. D
Which of the following characteristics of waves can a ripple tank be used to demonstrate?
I. Reflection
II. Refraction
III. Diffraction
- A. I, II and Ill
- B. ll and ll only
- C. l and lII only
- D. I and II only
In which of the following media is the speed of sound the least?
- A. Air
- B. Brass
- C. Water
- D. Wood
A transverse pulse of frequency 9 Hz traves 4.5m in 0.6 s. Calculate the wavelength of the pulse.
- A. 3.33 m
- B. 0.30 m
- C. 0.83 m
- D. 1.20 m
The wire of a platinum resistance thermometer has d resistance of 3.5\(\Omega\) at 0 °C and 10.52\(\Omega\) at 100°C. Calculate the temperature of the wire when its resistance is 7.5\(\Omega\).
- A. 78 °C
- B. 25 \(^o\)C
- C. 30\(^o\)C
- D. 57 \(^o\)C
Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 °C to 80 °C. [specific latent heat of fusion of ice= 3.36 x 10\(^5\) Jkg\(^{-1}\) specific heat capacity of water 4.2 x 10\(^3\) J kg\(^{-1}\) K\(^{-1}\)]
- A. 4.80 kJ
- B. 20.16 kJ
- C. 40.32 kJ
- D. 22.17 kJ
A small amount of air is introduced into the vacuum above the mercury in a mercury barometer tube. The mercury level goes down because the air molecules
- A. heat the mercury and make it expand
- B. increase the pressure above the mercury.
- C. cool the mercury and make it contract.
- D. decrease the pressure above the mercury
Which of the following graphs of a charge Q against potential difference V across the capacitor is correct?
- A. A
- B. B
- C. C
- D. D
A freshly demagnetized bar magnet is placed in the East-West direction to ensure that
- A. the molecular magnets remain randomly arranged.
- B. the molecular magnets are properly aligned
- C. it is affected by the earth's magnetic field
- D. the magnetic domains are within the earth's field
If the efficiency of a transformer is 100%, which of the following equations would be correct?
- A. N\(_p\)E\(_p\) = N\(_s\)E\(_s\)
- B. N\(_s\)I\(_p\)= N\(_p\)I\(_s\)
- C. N\(_s\)I\(_s\) = N\(_p\)I\(_p\)
- D. I\(_p\)E\(_s\) = I\(_s\)E\(_p\)
Which of the following statements about a moving object is correct?
- A. When accelerating, the resultant force acting on it must be equal to zero.
- B. There must always be a non-zero resultant force acting on it.
- C. At a steady velocity, the resultant force acting on it must be equal to zero
- D. At a steady velocity, the air resistance must be equal to zero.