The main function of a step-up transformer is to

Here are the solutions to your questions: 93. The main function of a step-up transformer is to A step-up transformer increases voltage and decreases current. The correct option is D. Increase voltage. 94. The rate at which electric charge flows past a point in a circuit is measured in The rate of flow of electric charge is defined as electric current. The SI unit for electric current is the ampere. The correct option is C. amperes. 95. The commercial unit of electrical energy is The commercial unit of electrical energy is the kilowatt-hour (kWh). The correct option is D. kilowatt hour. 96. A suitable material for the filament of a bulb should have A bulb filament needs to glow brightly without melting. This requires a high melting point and high resistance to generate sufficient heat and light. The correct option is C. high melting point and high resistance. 97. A lighting circuit is supplied through a 5A fuse. What is the maximum number of 75W, 240V bulbs that can be fixed in the circuit? Step 1: Calculate the total power the fuse can handle. The total power P_total is given by the product of voltage V and current I. P_total = V × I P_total = 240 \, V × 5 \, A = 1200 \, W Step 2: Calculate the maximum number of bulbs. The maximum number of bulbs n is the total power divided by the power of a single bulb P_bulb. n = P_totalP_bulb n = 1200 \, W75 \, W = 16 The maximum number of bulbs is B. 16. 98. Which of the following statements about boiling and evaporation is correct? Evaporation occurs at the surface of a liquid and can happen at any temperature below the boiling point. Boiling occurs throughout the liquid at a specific boiling temperature. The correct option is D. evaporation takes place at a lower temperature than boiling does. 99. A body weighs 120N in air, and 80N in water. What is the density of the body in kgm⁻³? Step 1: Calculate the buoyant force. The buoyant force F_B is the apparent loss of weight when the body is immersed in water. F_B = W_air - W_water F_B = 120 \, N - 80 \, N = 40 \, N Step 2: Calculate the volume of the body. The buoyant force is equal to the weight of the displaced fluid (F_B = _water V_body g). We can also relate the density of the body to the buoyant force. The density of the body _body can be found using the formula: _body = W_airF_B × _water Assuming the density of water _water = 1000 \, kg/m^3. _body = 120 \, N40 \, N × 1000 \, kg/m^3 _body = 3 × 1000 \, kg/m^3 = 3000 \, kg/m^3 The density of the body is D. 3000. 100. The principle of floatation states that The principle of floatation (Archimedes' principle for floating objects) states that a floating body displaces a weight of fluid equal to its own weight. The correct option is C. a floating body displaces its own weight of the fluid. 101. A mass of 400g was heated and immersed in an insulated copper calorimeter containing 200g of water at 16°C. If the temperature of the water and calorimeter of mass 400g goes to 60°C, find the initial temperature of the metal. (Specific heat capacities of aluminium, copper and water are 110J/KgK, 400J/KgK and 4200 J/KgK respectively.) Step 1: Identify the given values and specific heat capacities. Mass of metal m_m = 400 \, g = 0.4 \, kg Specific heat capacity of metal c_m = 110 \, J/kgK (assuming the metal is aluminium, as it's the first specific heat given) Mass of water m_w = 200 \, g = 0.2 \, kg Specific heat capacity of water c_w = 4200 \, J/kgK Mass of calorimeter m_c = 400 \, g = 0.4 \, kg Specific heat capacity of calorimeter c_c = 400 \, J/kgK (for copper) Initial temperature of water and calorimeter T_w,i = T_c,i = 16^ C Final temperature of mixture T_f = 60^ C Let the initial temperature of the metal be T_m,i. Step 2: Calculate the heat gained by the water. Q_w = m_w c_w (T_f - T_w,i) Q_w = 0.2 \, kg × 4200 \, J/kgK × (60^ C - 16^ C) Q_w = 0.2 × 4200 × 44 = 36960 \, J Step 3: Calculate the heat gained by the calorimeter. Q_c = m_c c_c (T_f - T_c,i) Q_c = 0.4 \, kg × 400 \, J/kgK × (60^ C - 16^ C) Q_c = 0.4 × 400 × 44 = 7040 \, J Step 4: Apply the principle of calorimetry. Heat lost by metal = Heat gained by water + Heat gained by calorimeter. Q_m = Q_w + Q_c m_m c_m (T_m,i - T_f) = Q_w + Q_c 0.4 \, kg × 110 \, J/kgK × (T_m,i - 60^ C) = 36960 \, J + 7040 \, J 44 × (T_m,i - 60) = 44000 Step 5: Solve for the initial temperature of the metal T_m,i. T_m,i - 60 = (44000)/(44) T_m,i - 60 = 1000 T_m,i = 1000 + 60 T_m,i = 1060^ C The initial temperature of the metal is 1060^ C. 102.a. What is a transformer? A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It is used to increase or decrease alternating current (AC) voltages. Send me the next one 📸