NSAA 2023 Physics PART B

• A.$\frac{Wh}{m}$
• B.$\frac{2Wh}{m}$
• C.$\frac{2mh}{W}$
• D.$2mWh$
• E.$\sqrt{2mWh}$
• F.$\sqrt{\frac{Wh}{m}}$
• G.$\sqrt{\frac{2Wh}{m}}$
• H.$\sqrt{\frac{2mh}{W}}$

Answer: G

• A.0.050 m
• B.0.10 m
• C.0.20 m
• D.5.0 m
• E.10 m
• F.20 m

Answer: F

A heater is connected in series with a dc power supply, a variable resistor and an ammeter in the circuit shown.

The variable resistor is adjusted until the reading on the ammeter is 0.50 A and the resistance of the heater is 8.0$\Omega$.

How much energy is converted to thermal energy in 5.0 minutes?

• A.10 J
• B.40 J
• C.160 J
• D.600 J
• E.2400 J
• F.9600 J

Answer: D

A circuit is set up as shown. All three resistors are identical.

When the switch is open, the reading on the ammeter is 1.0 A and the power transferred from the battery is 1.0 W.

The switch is now closed.

What is the new reading on the ammeter and what is the new power transferred from the battery?

• A.ammeter reading: 0.67 A, power transferred: 0.67 W
• B.ammeter reading: 0.67 A, power transferred: 1.3 W
• C.ammeter reading: 0.67 A, power transferred: 1.5 W
• D.ammeter reading: 0.67 A, power transferred: 2.0 W
• E.ammeter reading: 1.0 A, power transferred: 1.0 W
• F.ammeter reading: 1.0 A, power transferred: 1.5 W
• G.ammeter reading: 1.0 A, power transferred: 2.0 W
• H.ammeter reading: 1.0 A, power transferred: 3.0 W

Answer: F

• A.3.0
• B.6.0
• C.10
• D.17
• E.$\frac{20}{3}$
• F.$\frac{40}{3}$

Answer: B

A spring is initially unstretched. A force $F$ is used to stretch the spring. The extension $x$ and the energy $E$ stored in the stretched spring are measured for different values of $F$.

The graph shows how the energy $E$, in J, varies with the extension squared, $x^2$, in cm².

What is the magnitude of $F$ when the spring stores 0.015 J of energy?

• A.0.30 N
• B.0.60 N
• C.1.2 N
• D.1.5 N
• E.2.4 N
• F.3.0 N
• G.30 N
• H.60 N

Answer: B

• A.$^8_2$Z
• B.$^8_4$Z
• C.$^{12}_4$Z
• D.$^8_5$Z
• E.$^{12}_5$Z
• F.$^{16}_5$Z
• G.$^7_8$Z
• H.$^{16}_8$Z

Answer: E

• A.2.5 g cm⁻³
• B.3.0 g cm⁻³
• C.3.75 g cm⁻³
• D.7.5 g cm⁻³
• E.15 g cm⁻³
• F.33 g cm⁻³

Answer: B

A ray of light is directed horizontally towards two long, plane mirrors X and Y which are both at 45° to the horizontal. After two reflections the ray is travelling horizontally again.

Mirror X is now rotated clockwise through less than 45°. After this rotation, mirror X makes an angle $\theta$ with the horizontal, where $\theta < 45°$. The direction of the incident ray is unchanged.

In what direction and through what angle should mirror Y be rotated in order for the ray to be still horizontal and travelling to the right after reflecting from mirror Y?

• A.clockwise through an angle $\theta$
• B.anticlockwise through an angle $\theta$
• C.clockwise through an angle $2\theta$
• D.anticlockwise through an angle $2\theta$
• E.clockwise through an angle $45° - \theta$
• F.anticlockwise through an angle $45° - \theta$

Answer: E

• A.The expected numbers of atoms of X and Y are never equal.
• B.2 days
• C.3 days
• D.4 days
• E.6 days
• F.12 days

Answer: E

Two stones are held at rest at the same height at the top of a cliff.

One stone is released and falls freely under gravity.

A time $T$ later, the other stone is released and falls freely under gravity.

Which graph shows how the vertical distance separating the stones varies with time, from the moment the first stone is released and before the first stone lands?

(Assume that air resistance is negligible.)

• A.[Graph of separation vs time: linearly increasing from t=0 to t=T, then curving upwards with increasing gradient.]
• B.[Graph of separation vs time: zero from t=0 to t=T, then increasing linearly.]
• C.[Graph of separation vs time: zero from t=0 to t=T, then curving upwards with increasing gradient.]
• D.[Graph of separation vs time: zero from t=0 to t=T, then curving upwards but with decreasing gradient.]
• E.[Graph of separation vs time: parabolic curve from the origin, peaking at t=T, then decreasing.]
• F.[Graph of separation vs time: linearly increasing from origin to a peak at t=T, then linearly decreasing.]
• G.[Graph of separation vs time: zero from t=0 to t=T, then increasing linearly, then becoming horizontal (constant).]
• H.[Graph of separation vs time: zero from t=0 to t=T, then increasing with an S-shaped curve.]

Answer: A

A large, flat, metal plate is coated on one side with a layer of thermally insulating material of the same thickness $a$ as the metal plate.

The uninsulated top surface of the metal plate is maintained at a constant temperature $T_1$.

The bottom surface of the insulating material is maintained at a constant, lower temperature $T_2$.

The system is in equilibrium.

The diagram shows this arrangement.

Which graph could show how the temperature varies with distance from the top surface of the metal plate to the bottom surface of the insulating material?

• A.[Graph of temperature vs distance: a small linear drop in temperature from T1 over the distance 0 to a, followed by a large linear drop to T2 over the distance a to 2a.]
• B.[Graph of temperature vs distance: a large linear drop in temperature from T1 over the distance 0 to a, followed by a small linear drop to T2 over the distance a to 2a.]
• C.[Graph of temperature vs distance: a single straight line showing a linear drop from T1 at distance 0 to T2 at distance 2a.]
• D.[Graph of temperature vs distance: temperature is constant at T1 from distance 0 to a, then a linear drop to T2 over the distance a to 2a.]
• E.[Graph of temperature vs distance: temperature is constant at T1 from distance 0 to a, then a vertical drop to T2 at distance a, and then constant at T2 until 2a.]

Answer: A

• A.$T < 0°C$
• B.$T = 0°C$
• C.$0°C < T < 20 °C$
• D.$T = 20 °C$
• E.$20°C < T < 30 °C$
• F.$T = 30°C$
• G.$T > 30°C$

Answer: B

• A.1980 V
• B.6600 V
• C.22 000 V
• D.110 000 V
• E.550 000 V

Answer: C

A physicist introduces a thin piece of glass into the path of a laser beam in order to delay the beam. The light of the laser beam has a single wavelength $L$ in air.

While the beam is inside the glass it completes 10 more complete oscillations compared to the same beam passing through the same thickness of air.

The speed of light in air is $c$ and the speed of light in glass is $\frac{2}{3}c$.

What is the thickness of the glass?

• A.6.7$L$
• B.10$L$
• C.13$L$
• D.15$L$
• E.20$L$
• F.30$L$

Answer: E

• A.36 cm s⁻¹
• B.72 cm s⁻¹
• C.125 cm s⁻¹
• D.144 cm s⁻¹
• E.300 cm s⁻¹

Answer: D

A copper ring, with a small gap XY, rests in a uniform horizontal magnetic field. The ring lies in the plane of the page and the direction of the magnetic field is horizontal from left to right, as shown in the diagram.

A voltage is now applied across XY, such that X is connected to the positive terminal of the power supply and Y is connected to the negative terminal.

Which statement describes the motion of the ring immediately after the voltage is applied?

(Assume that the mechanism supporting the ring allows the ring to move freely and allows the voltage to be applied continuously.)

• A.The ring moves towards the bottom of the page.
• B.The ring moves towards the top of the page.
• C.The ring moves towards the left of the page.
• D.The ring moves towards the right of the page.
• E.The ring rotates about an axis perpendicular to the plane of the page in a clockwise direction.
• F.The ring rotates about an axis perpendicular to the plane of the page in an anti-clockwise direction.
• G.The ring rotates about an axis that is in the plane of the page and parallel to the field.
• H.The ring rotates about an axis that is in the plane of the page and perpendicular to the field.

Answer: H

A battery and two resistors X and Y are connected in series.

The power transferred by the battery is 6 W.

The resistance of X is 10 $\Omega$.

The voltage across Y is 4 V.

What is the current in the circuit?

• A.$\frac{2}{5}$ A
• B.$\frac{3}{5}$ A
• C.$\frac{3}{4}$ A
• D.1 A
• E.$\sqrt{\frac{3}{10}}$ A
• F.$\sqrt{\frac{3}{5}}$ A

Answer: B

• A.0.80 ms⁻²
• B.1.0 ms⁻²
• C.1.25 ms⁻²
• D.1.80 ms⁻²
• E.8.0 ms⁻²
• F.11.0 ms⁻²

Answer: C

• A.160 cm³
• B.180 cm³
• C.206 cm³
• D.225 cm³
• E.288 cm³
• F.315 cm³
• G.360 cm³
• H.405 cm³

Answer: A