Parallel circuit : $\frac{1}{R}$ = $\frac{1}{20} \;+ \frac{1}{30} = \frac{1}{12} $ = R = 12
Total resistance = 10 + 12 = 22 ohms
johnmulu answered the question on May 23, 2017 at 09:33
- The graph in Figure 9 shows the current-voltage characteristics of a certain device, X(Solved)
The graph in Figure 9 shows the current-voltage characteristics of a certain device, X
(i) State with a reason whether the device obeys Ohm's law
(ii) Determine the resistance of the device, X when the current through it is 60 mA
Date posted: May 23, 2017. Answers (1)
- The graph below shows the voltage-current relationship for a certain conductor. (Solved)
The graph below shows the voltage-current relationship for a certain conductor.
Determine the resistance of the conductor.
Date posted: May 23, 2017. Answers (1)
- Figure 4 shows an electrical circuit. When the switch is closed the ammeter reading is 0.3 A. (Solved)
Figure 4 shows an electrical circuit. When the switch is closed the ammeter reading is 0.3 A.
Determine the voltmeter reading.
Date posted: May 23, 2017. Answers (1)
- The ammeter in the circuit in Figure 11 has negligible resistance. When the switch S is closed, the ammeter reads 0.10 A. Determine the internal resistance of the battery. (Solved)
The ammeter in the circuit in Figure 11 has negligible resistance. When the switch S is closed, the ammeter reads 0.10 A. Determine the internal resistance of the battery.
Date posted: May 23, 2017. Answers (1)
- The internal resistance of the cell, E in Fig. 3 is 0.5 ohms. (Solved)
The internal resistance of the cell, E in Fig. 3 is 0.5 ohms.
Determine the ammeter reading when the switch, S is closed.
Date posted: May 23, 2017. Answers (1)
- The diagram in Fig. 2 represent an electric circuit in which five resistors are connected to be a battery of e.m.f. 4.0 V and of negligible internal resistance. (Solved)
The diagram in Fig. 2 represent an electric circuit in which five resistors are connected to be a battery of e.m.f. 4.0 V and of negligible internal resistance.
Determine:
(i) The current flowing through the 5.5 resistor
(ii) The potential difference between Y and Q.
Date posted: May 23, 2017. Answers (1)
- A thermistor, TH, is connected in parallel with a bulb as shown in Fig. 3.(Solved)
The bulb is lit. When the thermistor is steadily heated the brightness of the bulb reduces. Explain observation.
Date posted: May 23, 2017. Answers (1)
- Figure 10 shows a trolley of weight 20 N pulled by a force of 4 N from the bottom to the top of an inclined plane at a uniform speed. (Solved)
Figure 10 shows a trolley of weight 20 N pulled by a force of 4 N from the bottom to the top of an inclined plane at a uniform speed.
(i) State the value of the force acting downwards along the inclined plane.
(ii) Explain how the value in part (a)(i) is obtained.
Date posted: May 16, 2017. Answers (1)
- Figure 10 shows a pulley system used to raise a load by applying an effort of 500 N(Solved)
Figure 10 shows a pulley system used to raise a load by applying an effort of 500 N
State the:
(i) Velocity ratio of the system.
(ii) Purpose of pulley 2.
(iii) Given that the machine has an efficiency of 80%, determine the maximum load that can be raised.
Date posted: May 16, 2017. Answers (1)
- Figure 16 shows a screw jack whose screw has a pitch of 1 mm, and has a handle of 25 cm long.(Solved)
Figure 16 shows a screw jack whose screw has a pitch of 1 mm, and has a handle of 25 cm long.
Determine the velocity ratio of the jack.
Date posted: May 16, 2017. Answers (1)
- Figure 7 shows a mass of 30 kg being pulled from point P to point Q, with a force of 200 N parallel(Solved)
Figure 7 shows a mass of 30 kg being pulled from point P to point Q, with a force of 200 N parallel to an inclined plane. The distance between P and Q is 22.5 m. In being moved from P and Q the mass is raised through a vertical height of 7.5 m.
Determine the work done:
(I) By the force;
(II) On the mass;
(III) To overcome friction.
Date posted: May 16, 2017. Answers (1)
- Figure 9 shows a drum of mass 90 kg being rolled up a plane inclined at 25o to the horizontal. The force F applied is 420N and the distance moved by the drum along the plane is 5.2 m. (Solved)
Figure 9 shows a drum of mass 90 kg being rolled up a plane inclined at 25o to the horizontal. The force F applied is 420N and the distance moved by the drum along the plane is 5.2 m.
Determine:
(i) The work done by the effort;
(ii) The work done in raising the drum;
(iii) The efficiency of the inclined plane as a machine.
Date posted: May 16, 2017. Answers (1)
- Figure 5 shows two pulley systems being used to raise different loads. The pulleys are identical. (Solved)
Figure 5 shows two pulley systems being used to raise different loads. The pulleys are identical.
State one reason why system B may have a higher efficiency than system A.
Date posted: May 16, 2017. Answers (1)
- A body of mass 60 kg is pulled at a uniform velocity up smooth inclined surface as shown in Figure 11.(Solved)
A body of mass 60 kg is pulled at a uniform velocity up smooth inclined surface as shown in Figure 11.
If the distance moves along the incline is 4.0 m, determine work done by the force F.
Date posted: May 16, 2017. Answers (1)
- Figure 11 is a graph which shows how the vertical height through which a machine raises a mass 20 kg varies with time. (Solved)
Figure 11 is a graph which shows how the vertical height through which a machine raises a mass 20 kg varies with time.
Determine the power output of the machine after 40 seconds
Date posted: May 16, 2017. Answers (1)
- Figure 12 shows a body of weight 50N placed on a surface which is inclined at an angle of 30o to the horizontal. The body experiences a maximum frictional force of 29 N with the surface. (Solved)
Figure 12 shows a body of weight 50N placed on a surface which is inclined at an angle of 30o to the horizontal. The body experiences a maximum frictional force of 29 N with the surface.
Determine the force required to move the body, up the inclined with constant velocity
Date posted: May 16, 2017. Answers (1)
- Figure 13 shows a frictionless trolley of mass 2 kg moving with uniform velocity towards a wall.(Solved)
Figure 13 shows a frictionless trolley of mass 2 kg moving with uniform velocity towards a wall. At the front of the trolley is a spring whose spring constant is 25 Nm-1. The trolley comes to rest momentarily after compressing after compressing the spring by 3 cm and the rebounds from the wall.
(i) Determine
(I) The force exerted on the wall by the spring.
(II) The maximum acceleration of the trolley as it rebounds from the wall.
(ii) State the reason why the trolley acquires a constant velocity after it rebounds
Date posted: May 16, 2017. Answers (1)
- Figure 12 shows a lorry towing a trailer using a rope. (Solved)
Figure 12 shows a lorry towing a trailer using a rope.
The lorry exerts a force N on the trailer and the trailer exerts an equal but opposite force M on the lorry. The frictional force between the trailer and the road is F. Explain how the forces N, M and F enable the trailer to move
Date posted: May 16, 2017. Answers (1)
- Figure 5 is graph of net force on a body against its velocity as it falls through a liquid. (Solved)
Figure 5 is graph of net force on a body against its velocity as it falls through a liquid.
Determine the terminal velocity of the body.
Date posted: May 16, 2017. Answers (1)
- Two identical spherical steel balls are released from the top of two tall jars containing liquids L1 and L2 respectively. Figure 3 shows the velocity-time graph of the motion of the balls. (Solved)
Two identical spherical steel balls are released from the top of two tall jars containing liquids L1 and L2 respectively. Figure 3 shows the velocity-time graph of the motion of the balls.
Explain the nature of the curves and state why they are different.
Date posted: May 16, 2017. Answers (1)