HSSC physics

The dimensions of work are:

• 1 ML²T⁻²
• 2 MLT⁻²
• 3 ML⁻¹T⁻²
• 4 ML²T⁻¹

If the distance between two point charges is doubled, the force between them becomes:

• 1 Double
• 2 One quarter
• 3 One half
• 4 Four times

Capacitors of 6 μF and 3 μF are joined in series. The equivalent capacitance is:

• 1 4.5 μF
• 2 9 μF
• 3 18 μF
• 4 2 μF

The photoelectric effect supports which nature of light?

• 1 Particle nature
• 2 Magnetic nature
• 3 Wave nature only
• 4 Sound nature

The de Broglie wavelength of a particle is:

• 1 Independent of its momentum
• 2 Proportional to its momentum
• 3 Proportional to its mass squared
• 4 Inversely proportional to its momentum

The magnetic force on a charge moving parallel to a magnetic field is:

• 1 Zero
• 2 Maximum
• 3 Equal to qv
• 4 Equal to qB

If the length of a simple pendulum is made four times as large, its period becomes:

• 1 Twice as large
• 2 Half
• 3 Four times as large
• 4 One quarter

A sample of 80 g has a half-life of 5 days. How much is left after 15 days?

• 1 5 g
• 2 20 g
• 3 40 g
• 4 10 g

The power of a lens with a focal length of 0.5 m is:

• 1 0.5 D
• 2 1 D
• 3 5 D
• 4 2 D

Which of these waves is transverse?

• 1 Light
• 2 An ultrasonic wave in air
• 3 A compression wave in a spring
• 4 Sound in air

The dimensions of power are:

• 1 ML²T⁻²
• 2 ML²T⁻³
• 3 ML⁻²T³
• 4 MLT⁻³

If the mass on a spring is made four times as large, the period becomes:

• 1 Half
• 2 Four times as large
• 3 One quarter
• 4 Twice as large

At constant volume, doubling the absolute temperature of an ideal gas makes its pressure:

• 1 Half
• 2 Unchanged
• 3 Four times as large
• 4 Twice as large

The electric field at 3 m from a point charge of 2 μC is (k = 9 × 10⁹ N m²/C²):

• 1 2000 N/C
• 2 6000 N/C
• 3 200 N/C
• 4 18000 N/C

A 2 m wire carrying 4 A is placed at right angles to a field of 0.5 T. The force on it is:

• 1 1 N
• 2 4 N
• 3 2 N
• 4 16 N

A transformer has 100 turns in the primary and 400 in the secondary. A 20 V supply gives a secondary voltage of:

• 1 20 V
• 2 80 V
• 3 2000 V
• 4 5 V

The energy of a photon of frequency f is:

• 1 h ÷ f
• 2 hf²
• 3 f ÷ h
• 4 hf

An electron in an atom emits a photon when it:

• 1 Rises to a higher energy level
• 2 Stays at one level
• 3 Leaves the nucleus
• 4 Falls to a lower energy level

Binding energy per nucleon is greatest for nuclei whose mass number is close to:

• 1 4
• 2 238
• 3 56
• 4 120

After two half-lives, the fraction of the original radioactive nuclei left is:

• 1 1/4
• 2 0
• 3 1/8
• 4 1/2

In Young's double slit experiment, the fringes become wider when the wavelength of the light is:

• 1 Decreased
• 2 Unchanged
• 3 Increased
• 4 Zero

A tube closed at one end and 0.85 m long is excited at its lowest resonance (speed of sound 340 m/s). The frequency is:

• 1 100 Hz
• 2 200 Hz
• 3 400 Hz
• 4 50 Hz

According to Bernoulli's principle, in a moving fluid the pressure is lower where the speed is:

• 1 Zero
• 2 Higher
• 3 The same
• 4 Lower

If the radius of a planet is doubled and its mass stays the same, the acceleration due to gravity at its surface becomes:

• 1 Half
• 2 One quarter
• 3 Four times
• 4 Double

The angular momentum of a system is conserved when:

• 1 Its energy is constant
• 2 No force acts on it
• 3 Its speed is constant
• 4 No external torque acts on it

The kinetic energy of a 1000 kg car moving at 20 m/s is:

• 1 20000 J
• 2 200000 J
• 3 400000 J
• 4 10000 J

In a circuit with a capacitor connected to a DC source, the current in the steady state is:

• 1 Infinite
• 2 Zero
• 3 Maximum
• 4 Equal to V ÷ R

Lenz's law says that the induced current acts to:

• 1 Oppose the change in flux that produces it
• 2 Remain constant
• 3 Increase the change in flux
• 4 Stop the magnet

The rms value of an alternating voltage with a peak of 10 V is about:

• 1 14.1 V
• 2 7.07 V
• 3 10 V
• 4 5 V

An n-type semiconductor is made by doping with atoms that have:

• 1 Five valence electrons
• 2 Three valence electrons
• 3 Four valence electrons
• 4 Two valence electrons

The Carnot efficiency of an engine working between 500 K and 300 K is:

• 1 40%
• 2 20%
• 3 80%
• 4 60%

A ball is thrown vertically upward at 20 m/s (g = 10 m/s²). The time it takes to come back is:

• 1 4 s
• 2 10 s
• 3 2 s
• 4 8 s

The moment of inertia of a point mass m at distance r from the axis is:

• 1 m ÷ r²
• 2 mr
• 3 mr²
• 4 m²r

The energy stored in a spring of constant 200 N/m stretched by 0.1 m is:

• 1 2 J
• 2 0.1 J
• 3 1 J
• 4 20 J