What is a semiconductor, distinguish between p-type and n-type semiconductors, and calculate electron flow given current and time?

Here are the answers to the questions: Question 1: a) i) What is a semiconductor? A semiconductor is a material that has electrical conductivity between that of a conductor (like copper) and an insulator (like glass). Its conductivity can be controlled by doping with impurities or by changing temperature. a) ii) Distinguish between a p-type semiconductor and an n-type semiconductor. A p-type semiconductor is created by doping a pure semiconductor with trivalent impurities (e.g., boron), resulting in a majority of holes as charge carriers. An n-type semiconductor is created by doping a pure semiconductor with pentavalent impurities (e.g., phosphorus), resulting in a majority of electrons as charge carriers. a) iii) Name an application of a combination of a p-type and n-type semiconductor. A common application is a diode (p-n junction), which allows current to flow in only one direction. Other applications include transistors and solar cells. b) Calculate the number of electrons that flow through a conductor if a current of 2 A flows for 4 s (charge on an electron = 1.6 × 10^-19 C). Step 1: Calculate the total charge (Q) that flows. Q = It Q = (2 A)(4 s) Q = 8 C Step 2: Calculate the number of electrons (n) using the total charge and the charge of a single electron (e). Q = ne n = (Q)/(e) n = 8 C1.6 × 10^-19 C n = 5 × 10^19 The number of electrons is 5 × 10^19. Question 2: a) State the law of conservation of linear momentum. The law of conservation of linear momentum states that in an isolated system, the total linear momentum remains constant if no external forces act on the system. b) i) Calculate the momentum of the bullet. Given: Mass of bullet m_b = 0.05 kg, velocity of bullet v_b = 900 m/s. Step 1: Use the formula for momentum (p = mv). p_b = m_b v_b p_b = (0.05 kg)(900 m/s) p_b = 45 kg m/s The momentum of the bullet is 45 kg m/s. b) ii) Calculate the recoil velocity of the gun. Given: Mass of gun m_g = 4 kg. Step 1: Apply the law of conservation of linear momentum. The initial momentum of the gun-bullet system is zero. After firing, the total momentum must still be zero. m_b v_b + m_g v_g = 0 Step 2: Substitute the known values and solve for the recoil velocity of the gun (v_g). (0.05 kg)(900 m/s) + (4 kg)v_g = 0 45 kg m/s + (4 kg)v_g = 0 (4 kg)v_g = -45 kg m/s v_g = -45 kg m/s4 kg v_g = -11.25 m/s The negative sign indicates that the gun recoils in the opposite direction to the bullet. The recoil velocity of the gun is 11.25 m/s. Question 3: a) i) Name the pressures exerted at points A and B. Point A: Gas pressure (from the gas supply). Point B: Atmospheric pressure (as it's open to the atmosphere). a) ii) Calculate the excess pressure of point B. Given: Density of mercury = 13,500 kg/m^3. From Figure 1, the mercury level in the left arm (connected to gas) is lower than in the right arm (open to atmosphere). This indicates the gas pressure is higher than atmospheric pressure. The height difference (h) between the mercury levels appears to be approximately 4 cm. Assumption: Height difference h = 4 cm = 0.04 m. Step 1: Calculate the excess pressure (pressure difference) using the formula P = gh. P = gh P = (13,500 kg/m^3)(9.8 m/s^2)(0.04 m) P = 5292 Pa The excess pressure is 5292 Pa. b) Name one instrument that is an application of the U-tube. A manometer is an instrument that uses a U-tube to measure pressure differences. Question 4: a) State the conditions necessary for the system to be in equilibrium. For a system to be in equilibrium, two conditions must be met: • The net force acting on the system must be zero (translational equilibrium). • The net torque (or sum of moments) about any point must be zero (rotational equilibrium). b) If the see-saw M, a" has negligible weight, calculate the distance, T. From Figure 2, for rotational equilibrium, the sum of clockwise moments must equal the sum of anticlockwise moments about the pivot. Anticlockwise moment = 10 N × 0.5 m = 5 Nm. Clockwise moment = 20 N × T. Step 1: Set the moments equal. 20 N × T = 10 N × 0.5 m 20T = 5 Step 2: Solve for T. T = (5)/(20) T = 0.25 m The distance T is 0.25 m. c) i) Calculate the upward force, R, acting at the pivot. For translational equilibrium, the sum of upward forces must equal the sum of downward forces. Downward forces = 10 N + 20 N = 30 N. Upward force = R. Step 1: Set upward forces equal to downward forces. R = 10 N + 20 N R = 30 N The upward force R acting at the pivot is 30 N. c) ii) Draw a free-body diagram of the forces acting, showing that the system is stable. A free-body diagram for the beam would show: • A downward force of 10 N at 0.5 m to the left of the pivot. • A downward force of 20 N at 0.25 m to the right of the pivot. • An upward force of 30 N at the pivot. The system is stable because it is in equilibrium, meaning the net force and net torque are zero. If slightly disturbed, it would tend to return to its equilibrium position. ` <-- 0.5 m --> <-- 0.25 m --> | | | | | | V 10 N ^ 30 N V 20 N ----------------------------------- (Pivot) ` Question 5: Figure 3 shows an electric circuit. The circuit consists of a voltage source (V = 6 V), an ammeter, and three resistors, each with resistance R = 2 . Two resistors are connected in parallel, and this parallel combination is connected in series with the third resistor. i) The combined resistance of the above circuit. Step 1: Calculate the equivalent resistance of the two parallel resistors (R_p). (1)/(R_p) = (1)/(R) + (1)/(R) (1)/(R_p) = (1)/(2 ) + (1)/(2 ) (1)/(R_p) = (2)/(2 ) R_p = 1 Step 2: Calculate the total resistance (R_total) by adding the parallel equivalent resistance to the series resistor. R_total = R_p + R R_total = 1 + 2 R_total = 3 The combined resistance of the circuit is 3 . ii) The current flowing through the ammeter. Given: Voltage V = 6 V, Total resistance R_total = 3 . Step 1: Use Ohm's Law (I = (V)/(R_total)). I = (V)/(R_total) I = 6 V3 I = 2 A The current flowing through the ammeter is