Dependent Resistors Light Dependent Resistors (LDR) are also called photoresistors. They are made of high resistance semiconductor material. When light hits the device‚ the photons give electrons energy. This makes them jump into the conductive band and thereby conduct electricity. A photoresistor or light-dependent resistor (LDR) or photocell is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words‚ it exhibits photoconductivity
Premium Resistor Electrical resistance Semiconductor
circuit elements around the chosen loop. The figure contains two junctions (where three or more wires meet)--they are at the ends of the resistor labeled R3 . The battery supplies a constant voltage Vb ‚ and the resistors are labeled with their resistances. The ammeters are ideal meters that read I1 and I2 respectively. The direction of each loop and the direction of each current arrow that you draw on your own circuits are arbitrary. Just assign voltage drops consistently and sum both voltage drops
Free Resistor Series and parallel circuits Ohm's law
stationary‚ there is no back e.m.f. in the armature. Consequently‚ if the motor is directly switched on to the mains‚ the armature will draw a heavy current (Ia = V/Ra) because of small armature resistance. As an example‚ 5 H.P.‚ 220 V shunt motor has a full-load current of 20 A and an armature resistance of about 0.5 . If this motor is directly switched on to supply‚ it would take an armature current of 220/0.5 = 440 A which is 22 times the full-load current. This high starting current may result
Premium Electric motor Electrical resistance Schematic
remain constant: I∞V Exactly how much current flows in a wire depends not only on the voltage‚ but also on the resistance the wire offers to the flow of electrons. Electrons are showed down because of interactions with the atoms of the wire. The higher the resistance‚ the less the current for a given voltage V. Resistance is defined as; Where R is the resistance of a wire or any other device‚ V is the potential difference across the device and I is the current that flows through
Premium Ohm's law Resistor Electric current
Chapter 1 Principles of Electricity Practice Problems 1. One coulomb of charge passes a point every 20 seconds. Calculate the value of the current through the point. I = Q/t = 1 coulomb/20 seconds = 0.05C/s = 0.05 A 2. A total charge of 2.5x10^-3 C passes a point every 40 seconds. Calculate the value of the current through the point. I=Q/t = 2.5C/40s = 0.0625C/s = 0.0625 A 4. A total charge of 50x10^-3 C passes a point every 2.5 seconds. Calculate the
Premium Resistor Ohm's law Electrical resistance
conductance and resistance? They are the reciprocals of one another. 2. What is the symbol for mhos? ______upside down omega sign (Ω)___ 3. What other unit‚ other than mhos‚ can conductance be measured in? What is its symbol? Siemens‚ S 4. What is the total resistance of a circuit with three parallel resistors with the values below? Gt= G1+G2+G3= 0.5mS+0.25mS+0.75mS= 0.0015 x 10^-3= 1.5mS Rt= 1/Gt= 1/1.5mS= 667Ω 5. Use the reciprocal method to calculate the total resistance of the circuit
Premium Measurement Resistor Series and parallel circuits
PHYSICS II ELECTRICITY‚ MAGNETISM‚ SOUND‚ AND LIGHT SERIES CIRCUIT In this unit you’ll begin learning how to analyze circuits. Circuit analysis means looking at a schematic diagram for a circuit and computing the voltage‚ current‚ or power for any component in that circuit. Closely related to the task of circuit analysis is the task of troubleshooting‚ which means figuring out what is wrong in a circuit that is not working correctly. Analyzing and troubleshooting go hand in hand; when a circuit
Free Resistor Electrical resistance Series and parallel circuits
Procedure Part I Wire Resistance: As wire length (cm) increases‚ the resistance (Ω) increases As wire area (cm2) increases‚ the resistance (Ω) decreases As wire resistivity (Ωcm) increases‚ the resistance (Ω) increases Procedure Part II: Ohm’s Law: Electricity‚ Magnets‚ and Circuits Ohm’s Law mA is milliamps‚ and 1000 milliamps equals one Ampere. Move the potential (volts) and resistance (ohms) sliders and observe the current (amps) As voltage increases‚ current increases. As resistance increases‚ current
Premium Volt Incandescent light bulb Electric current
Coursework - Resistance of a Wire Coursework Introduction (Theory) In this piece of Coursework I am going to investigate the resistance in a piece of wire. Resistance is the force that slows down the flow of electrons; this can be due to electrons colliding. The total length of the wires will affect the amount of resistance. The longer the wire‚ the more resistance that there will be. This is also true for thickness of wire; the thinner the wire is the more resistance. Resistance is measured
Premium Electric current Ohm's law Electrical resistance
SENIOR SECONDARY EXAMINATION Scheme of Physics Practical Examination Duration: 3 hours Maximum Marks: 20 There will be a practical examination of 20 marks apart from the theory examination. The distribution of 20 marks is as follows: (i) (ii) (iii) Viva Record Book Two Experiments 4 Marks 2 Marks 14 Marks Note: There are 30 experiments in three Groups A‚ B and C. In the practical; examination candidates has To do two experiments which should not be from the same group and each experiment carries
Premium Optics Refractive index Electrical resistance