The energy associated with the emitted photon when a mercury atom changes from one state to another is 3.3 ev. calculate the frequency of the photon.
[e = 1.6 x 10-19c; h = 6.6 x 10-13js]
- A. 1.3 x 10-15 Hz
- B. 3.1 x 1052 Hz
- C. 3.2 x 10-53 Hz
- D. 8.0 x 1014 Hz
I. Work done by load is always less than the work done by effort.
II. All machines are made of levers, pulleys, screws and gear wheels.
III. A fishing rod is a machine.
Iv. Effort is always larger than load.
which of statements above about machines are true?
- A. II and III
- B. III and IV
- C. I and III
- D. II and iv
The correct unit of energy density is?
- A. kg m3 s-2
- B. kg m2 s-2
- C. kg m-3 s-2
- D. kg m-1 s-2
The component of vector X along the direction of vector Y is zero when
- A. X and Y are in opposite directions to each other
- B. X is at an angle of 45° to Y
- C. X is perpendicular to Y
- D. X and Y are parallel to each other
If the radius of the earth is 6.4 x 10\(^6\)m, the escape velocity of a satellite from the earth is?
[g = 10 ms-2]
- A. 1.13 x 104 ms-1
- B. 9.00 x 103 ms-1
- C. 8.00 x 103 ms-1
- D. 1.27 x 104 ms-1
In an experiment to determine terminal velocity, as the pressure increases, the viscosity off a liquid
- A. increases
- B. decreases
- C. increases then decreases
- D. remains constant
The motion of smoke particles from a chimney is typical of?
- A. random motion
- B. circular motion
- C. rotational motion
- D. oscillatory motion
An ammeter of resistance 5Ω has a full-scale deflection when a current of 50 mA flows in it. The value of the resistor required to adapt it to measure a current of 5 A is?
- A. 0.25Ω
- B. 5.00Ω
- C. 19.80Ω
- D. 0.05Ω
When a certain a.c supply is connected to a lamp, it lights with the same brightness as it does with a 12 V d.c battery. Then r.m.s value of the a.c supply is?
- A. 12.0 V
- B. 3.5 V
- C. 17.0 V
- D. 8.5
During electrolysis, 2.0 g of a metal is deposited using a current of 0.5 A in 3 hours. The mass of the same metal which can be deposited using a current of 1.5 A in 1 hour is?
- A. 1.0 g
- B. 0.5 g
- C. 3.0 g
- D. 2.0 g
The electrolyte in the Nickei-iron (Nife) accumulator is
- A. potassium hydroxide solution
- B. dilute tetraoxosulphate(VI)acid
- C. copper tetraoxosulphate(VI)solution
- D. ammonium chloride solution
When an a.c. voltage is applied to a capacitor, no power is consumed because the current
- A. leads the voltage by 90°
- B. lags behind the voltage by 90°
- C. and voltage are in phase
- D. and voltage are 180° out of phase
If the capacitance of an capacitor is C = (εA)/d, which of the following parameters is varied when a variable capacitors is used for tuning radio sets?
- A. constant (ε) and area
- B. area and distance.
- C. constant (ε) only
- D. distance only
An electric heater with a p.d of 240 V connected across its terminals has a total resistance of 960Ω. find the power rating of the heater.
- A. 0.25 W
- B. 4.00 W
- C. 38.40W
- D. 60.00W
The main purpose of the transformer in an a.c radio set is to?
- A. increase power to the radio
- B. step up the voltage
- C. convert energy from a.c to d.c
- D. step down the voltage
The production and type of charge of a body can only be accounted for by the?
- A. deficiency or surplus of electrons
- B. equibrium in protons and neutrons
- C. deficiency or surplus of protrons
- D. deficiency or surplus of neutrons
A cell of internal resistance r is connected to an external resistor R. The conductor for maximum power transfer is?
- A. R < r
- B. R = r
- C. R = 2r
- D. R > r
A drop of petrol makes a finger colder than a drop of water would because?
- A. petrol takes its latent heat of veporization from the finger
- B. petrol takes its latent heat of fusion from the finger
- C. water is more viscious than petrol
- D. water has higher surface tension dan petrol
what is likely to happen if the glass of a thermometer expands more upon heating than the liquid inside?
- A. the glass will break
- B. the glass will shrink
- C. the liquid will rise up in the stem
- D. the liquid will go down in the stem
The thermos flask is designed to?
- A. prevent heat loss or gain by conduction, convection amd radiation
- B. store hot tea or water
- C. prevent heat gain by conduction, convection and radiation
- D. prevent head lost conduction, convention and radiation
An immersion heater rated 2.0A, 240V is used to boil water from temperature 52°c to 100°c. If the mass of the water is 2.5kg. determine the time taken to boil the water.
[specific heat capacity of water = 4.2 x 103 jkg-1 k-1]
- A. 1.05 x 103s
- B. 1.05 x 105s
- C. 1.05 x 102s
- D. 1.05 x 104s