لمّاح✨ SEU

Question 30 Question: Calculate the change in the internal energy of a system, which gets $800\text{ J}$ of heat from the surrounding and work done on the system is $60\text{ J}$. Answer: B - 860 J

Question 21 Question: If the wave number of a certain wave is $12.00\text{ m}^{-1}$, and the frequency is $4.00\text{ Hz}$. The speed of the wave is: Answer: A - 2.09 m/s Question 22 Question: As a person runs towards the speaker, the frequency he hears: Answer: B - Higher Question 23 Question: A mass–spring system has a force constant of a spring $k = 100\text{ N/m}$ and mass $m = 1\text{ kg}$. What is the period? Answer: C - 0.63 s Question 24 Question: When displacement is maximum in SHM, acceleration is: Answer: A - Maximum and opposite direction Question 25 Question: An engine transfers $2000\text{ J}$ of energy from a hot reservoir during a cycle and transfers $600\text{ J}$ as exhaust to a cold reservoir. Calculate the work of this engine in one cycle? Answer: A - 1400 J Question 26 Question: Calculate the thermal efficiency of a heat engine that gains $2000\text{ J}$ of energy and loses $400\text{ J}$ during one period Answer: A - 80 % Question 27 Question: If the temperature of a room is $333.4\text{ K}$, determine the room's temperature in degree Celsius? Answer: C - 60.25 °C Question 28 Question: Carnot cycle is a/an Answer: D - Ideal cycle Question 29 Question: Absolute zero is equal to Answer: B - -273.15 °C

Question 11 Question: An electric heater draws a current of $12\text{ A}$ on a $120\text{ V}$ line. Find the power consumed in the heater? Answer: D - 1440 W Question 12 Question: What is the magnitude of electric field between the plates of oppositely charged plates that are separated by $2\text{ cm}$, if the potential difference of $300\text{ V}$ exists between the plates. Answer: C - 1.5x $10^4$ V/m Question 13 Question: In a circuit in which the resistors are connected in parallel, the voltage across each resistor is: Answer: C - The same Question 14 Question: Calculate the power consumed in a resistor which has $12\text{ volts}$ and a resistance of $6\Omega$? Answer: A - 24 W Question 15 Question: When a charged particle is moving in a circular path located in the magnetic field B with a velocity (v), then the magnetic force $\text{F}_B$ for this particle will be directed to Answer: A - The center of the circular path. Question 16 Question: Determine electrical potential at a point $0.40\text{ m}$ from a $+30\ \mu\text{C}$ point charge? Answer: C - 6.75×10⁵ V Question 17 Question: The refracted light vanishes at the critical angle and the reflection becomes .......... for any angle $\theta_1 > \theta_{\text{critical}}$ Answer: D - 100% Question 18 Question: diffraction of light occurs when the light passes through the opening in a barrier (d) which has the following condition Answer: D - d = $\lambda$ Question 19 Question: A wave is described by the function: $\text{Y}(x, t) = 0.3 \sin(5x - 30t)$. Find an amplitude and an angular frequency $\omega$ of this wave? Answer: A - 0.3 m, 30 rad/s Question 20 Question: When a ray of light enters a medium, the velocity of light becomes $2.3\times10^8\text{ m/s}$. Determine the refractive index of the medium. (Hint: speed of light in vacuum $\text{c} = 3.00\times10^8\text{ m/s}$) Answer: D - 1.3

Question 11 Question: An electric heater draws a current of $12\text{ A}$ on a $120\text{ V}$ line. Find the power consumed in the heater? Answer: D - 1440 W (Explanation: $P = I \times V = 12\text{ A} \times 120\text{ V} = 1440\text{ W}$) Question 12 Question: What is the magnitude of electric field between the plates of oppositely charged plates that are separated by $2\text{ cm}$, if the potential difference of $300\text{ V}$ exists between the plates. Answer: C - 1.5x $10^4$ V/m (Explanation: $E = \frac{\Delta V}{d} = \frac{300\text{ V}}{0.02\text{ m}} = 15000\text{ V/m} = 1.5 \times 10^4\text{ V/m}$) Question 13 Question: In a circuit in which the resistors are connected in parallel, the voltage across each resistor is: Answer: C - The same Question 14 Question: Calculate the power consumed in a resistor which has $12\text{ volts}$ and a resistance of $6\Omega$? Answer: A - 24 W (Explanation: $P = \frac{V^2}{R} = \frac{12^2}{6} = \frac{144}{6} = 24\text{ W}$) Question 15 Question: When a charged particle is moving in a circular path located in the magnetic field B with a velocity (v), then the magnetic force $\text{F}_B$ for this particle will be directed to Answer: A - The center of the circular path. Question 16 Question: Determine electrical potential at a point $0.40\text{ m}$ from a $+30\ \mu\text{C}$ point charge? Answer: C - 6.75$\times10^5$ V (Explanation: $V = \frac{K \cdot q}{r} = \frac{9 \times 10^9 \times 30 \times 10^{-6}}{0.40} = 675000\text{ V} = 6.75 \times 10^5\text{ V}$) Question 17 Question: The refracted light vanishes at the critical angle and the reflection becomes .......... for any angle $\theta_1 > \theta_{\text{critical}}$ Answer: D - 100% Question 18 Question: diffraction of light occurs when the light passes through the opening in a barrier (d) which has the following condition Answer: D - d = $\lambda$ (or d $\approx \lambda$, where the opening is comparable to the wavelength) Question 19 Question: A wave is described by the function: $\text{Y}(x, t) = 0.3 \sin(5x - 30t)$. Find an amplitude and an angular frequency $\omega$ of this wave? Answer: A - 0.3 m, 30 rad/s Question 20 Question: When a ray of light enters a medium, the velocity of light becomes $2.3\times10^8\text{ m/s}$. Determine the refractive index of the medium. (Hint: speed of light in vacuum $\text{c} = 3.00\times10^8\text{ m/s}$) Answer: D - 1.3 (Explanation: $n = \frac{c}{v} = \frac{3.00 \times 10^8}{2.3 \times 10^8} \approx 1.3$)