The vacuum and silvered wall surfaces of a vacuum flask walls are respectively
Trả lời
(B)
prevent conduction and convection and minimize radiation
2
The magnitude of the acceleration of a moving object is equal to the
Trả lời
(B)
gradient of a velocity-time graph
3
In which of the following states is MAXIMUM pressure exerted on a person
Trả lời
(B)
Standing on one foot
4
What are cathode rays?
Trả lời
(A)
Stream of electrons
5
The capacitance of a parallel plate capacitor
Trả lời
(D)
is greater with dielectric between the plates than without dielectric.
6
The diagram above illustrates the motion of a cyclist from P to R. The distance travelled is determined by the
Trả lời
(B)
area under PQR
7
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
Trả lời
(D)
decreases and the frequency remains the same
8
The function of a fuse in an electric circuit is to
Trả lời
(A)
break the circuit when the current exceeds a certain value
9
A body moves with uniform velocity when the resultant force on it is
Trả lời
(C)
equal to zero
10
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?
Trả lời
(A)
No external force acts on the system and there is no change in mass of the system.
11
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.
Trả lời
(A)
5.3 N
12
To convert a milli-ammeter to an ammeter, a resistor of low value is necessary to connect a resistor of
Trả lời
(C)
low value in parallel with it
13
An object is placed 1.5 m from a plane mirror. How far is the image from the object?
Trả lời
(A)
3.0 m
14
Chromatic aberration in lenses can be corrected by using a combination of
Trả lời
(A)
diverging and converging lenses.
15
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\(^3\)]
Trả lời
(B)
0.450 g/cm\(^3\)
16
A temperature of 60º C is equivalent to
Trả lời
(B)
140ºF
17
All of the following uses are practical applications of x-ray except
Trả lời
(B)
determining the depth of a mine
18
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\(^{-2}\)]
Trả lời
(A)
2.25 x 10\(^{-1}\)N
19
In the circuit diagram above, which lamp causes the other to go off?
Trả lời
(D)
S
20
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.
Trả lời
(A)
1.55 x 10\(^2\)N
21
For a convex lens to form a real image, the distance between the object and the screen will be:
Trả lời
(C)
twice the focal length of the lens
22
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
Trả lời
(C)
5V
23
A 2 μF capacitor is connected directly across a 150 V\(_{rms}\), 60 Hz A.C source. Calculate the r m s value of the current.
Trả lời
(A)
0.113 A
24
A body of mass, m is projected vertically upward with a velocity, y. At what position will the potential energy be maximum?
Trả lời
(C)
\(\frac{y^2}{2g}\)
25
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]
Trả lời
(A)
4.8 x 10\(^{14}\)Hz
26
An object 2.0 cm high is placed at the radius of curvature of a concave mirror such that it is perpendicular to the principal axis of the mirror. Determine the height of the image.
Trả lời
(D)
2.0 cm
27
The diagram above illustrates two boxes P and Q of masses 27.3 kg and 6.2 kg respectively on a smooth horizontal surface. If a force F of 150 N is applied to the combined forces, calculate the acceleration.
Trả lời
(A)
4.5 ms\(^{-2}\)
28
A boy of mass 40 kg jumps off a stationary skateboard and moves horizontally with a speed of 1.5 m/s while the skateboard moves in the opposite direction with a speed of 20 m/s. Calculate the mass of the skateboard.
Trả lời
(C)
3 kg
29
The depolarizing agent in a Leclanché cell is
Trả lời
(B)
manganese (IV) oxide.
30
Which of the following terms has different dimension from the others?
Trả lời
(D)
Torque
31
A capacitor described as a mica capacitor has
Trả lời
(C)
a dielectric made of mica
32
In which of the following devices is the thermal expansion considered a disadvantage?
Trả lời
(D)
Balance wheel of a watch
33
The inside portion of a hollow metal sphere of diameter 20 cm is polished. The portion will therefore form a
Trả lời
(D)
Convex mirror of focal length 5cm
34
Which of the following statements about a projectile is not correct?
Trả lời
(C)
The range of a projectile is independent of the acceleration due to gravity.
35
Atmospheric pressure decreases with an increase in altitude because:
Trả lời
(D)
Interaction among air molecules decreases due to less quantity of air.
36
The main difference between X-rays and gamma rays is in their
Trả lời
(D)
mode of production.
37
The phenomenon used for explaining the formation of a rainbow in the sky is
Trả lời
(D)
dispersion.
38
Which of the following modes is the most economical method of transmitting electrical power over a long distance?
Trả lời
(A)
Alternating current at high voltage and low current.
39
The correct sequence of ionization power of alpha particle, gamma ray, and beta particle respectively is
Trả lời
(D)
high, low, medium.
40
Four pieces of constantan wire, marked E, F, G, and H, each of length 1.0m, are at the temperature. Their respective diameters are 1 mm, 2 mm, 6 mm, and 10 mm. Which wire has the highest resistance?
Trả lời
(A)
E
41
The maximum displacement of particles from equilibrium position in a wave motion is known as
Trả lời
(B)
amplitude.
42
A non-conducting vessel contains a liquid of mass 70 g at 25º C. Another 70.0g of the same liquid at 35ºC is quickly poured into the vessel. Determine the final temperature of the mixture
Trả lời
(C)
30ºC
43
A galvanometer of full-scale deflection 10 mA has a resistance of 5\(\Omega\). Calculate the shunt needed to convert it to measure currents of 2 A.
Trả lời
(A)
0.025\(\Omega\)
44
In storing magnets, the keeper is used to
Trả lời
(B)
reduce self demagnetization
45
Which of the following factors does not affect the speed of sound?
