https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/what_is_voltage 2026-04-16T15:20:38.862861542Z Voltage (electric potential difference) The electric potential at a point represents the electric potential energy per unit charge that a particle would have at that location. The difference in electric potential between two points is called voltage. It's measured in volts (V), equivalent to joules per coulomb (J/C). When comparing two points, the point with the higher electric potential is labelled positive (+), and the point with the lower electric potential is negative (-). If two points are at the same electric potential, the voltage between them is zero. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/d5c4aa26-c7b6-4d1b-81e5-315e5bcb7aa7_1280_720_base.png Voltage (electric potential difference) The electric potential at a point represents the electric potential energy per unit charge that a particle would have at that location. The difference in electric potential between two points is called voltage. It's measured in volts (V), equivalent to joules per coulomb (J/C). When comparing two points, the point with the higher electric potential is labelled positive (+), and the point with the lower electric potential is negative (-). If two points are at the same electric potential, the voltage between them is zero. https://cdn.kastatic.org/ka-youtube-converted/NT6LYNq3jRE.mp4/NT6LYNq3jRE.mp4 767 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/electric_current 2024-05-14T13:21:48.153833747Z Electric current Electric current is the net rate that charge flows through a cross-sectional area. Current is measured in amperes (A), equivalent to coulombs per second (C/s). Current flows when there is an electric potential difference (voltage) between two points, and there are charge carriers that are free to move between those points. Electrical conductors (metals) contain electrons that are free to move. Electrons are the drifting particles in a current-carrying wire, but conventional current is defined as the direction that positive charge would flow. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/c378c0d0-d325-46f8-89e6-2bf7a9b6cb55_1280_720_base.png Electric current Electric current is the net rate that charge flows through a cross-sectional area. Current is measured in amperes (A), equivalent to coulombs per second (C/s). Current flows when there is an electric potential difference (voltage) between two points, and there are charge carriers that are free to move between those points. Electrical conductors (metals) contain electrons that are free to move. Electrons are the drifting particles in a current-carrying wire, but conventional current is defined as the direction that positive charge would flow. https://cdn.kastatic.org/ka-youtube-converted/6K1Bl0cqecE.mp4/6K1Bl0cqecE.mp4 809 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/electric-circuits-part-1 2026-06-14T15:20:38.731319356Z Intro to electric circuits Electric circuits are paths through which electric current can flow. Circuits are composed of specific building blocks known as circuit elements. Circuit elements include batteries and other voltage sources, wires, resistors, light bulbs and LEDs, and switches. Ammeters and voltmeters can be used to measure current and voltage in a circuit, respectively. An open circuit contains a broken path, preventing current flow. A short circuit contains a path with negligible resistance, resulting in very high current. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/69deb774-2257-4c09-8f24-246ac585e3a5_1280_720_base.png Intro to electric circuits Electric circuits are paths through which electric current can flow. Circuits are composed of specific building blocks known as circuit elements. Circuit elements include batteries and other voltage sources, wires, resistors, light bulbs and LEDs, and switches. Ammeters and voltmeters can be used to measure current and voltage in a circuit, respectively. An open circuit contains a broken path, preventing current flow. A short circuit contains a path with negligible resistance, resulting in very high current. https://cdn.kastatic.org/ka-youtube-converted/Nbb5Lw14wvo.mp4/Nbb5Lw14wvo.mp4 718 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/electric-circuits-part-2 2026-06-14T15:20:38.731319356Z Series and parallel circuits Circuit elements can be connected in series or in parallel. A series connection exists when elements are joined along a single chain. The same current flows through every element in the chain. A parallel connection exists when elements are connected across the same two points in a circuit, with no other components between them. The same voltage exists across each element in a parallel connection. Real-world circuits often utilize a combination of both series and parallel connections. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/605cc969-d321-45ea-b107-17be8fc8e9c1_1280_720_base.png Series and parallel circuits Circuit elements can be connected in series or in parallel. A series connection exists when elements are joined along a single chain. The same current flows through every element in the chain. A parallel connection exists when elements are connected across the same two points in a circuit, with no other components between them. The same voltage exists across each element in a parallel connection. Real-world circuits often utilize a combination of both series and parallel connections. https://cdn.kastatic.org/ka-youtube-converted/1ASc6piVKhQ.mp4/1ASc6piVKhQ.mp4 852 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/ohms-law 2026-06-09T12:40:46.120135017Z Ohm's law Through experiment, we can uncover the relationship between the current through a circuit element and the voltage across it. Measurements show that the current is equal to the voltage divided by the element’s resistance (I=ΔV/R). This relationship is called Ohm’s law. Since the current is proportional to the voltage, a graph of current through an element versus the voltage across it is a straight line. The slope of the line is the element’s conductance, which is the reciprocal of resistance. Though many circuit elements obey Ohm’s law, some do not. Such components are called non-ohmic. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/0fd79a2e-d95b-4e14-a160-3f041bbf0a1e_1280_720_base.png Ohm's law Through experiment, we can uncover the relationship between the current through a circuit element and the voltage across it. Measurements show that the current is equal to the voltage divided by the element’s resistance (I=ΔV/R). This relationship is called Ohm’s law. Since the current is proportional to the voltage, a graph of current through an element versus the voltage across it is a straight line. The slope of the line is the element’s conductance, which is the reciprocal of resistance. Though many circuit elements obey Ohm’s law, some do not. Such components are called non-ohmic. https://cdn.kastatic.org/ka-youtube-converted/FuIn1L3qeqI.mp4/FuIn1L3qeqI.mp4 738 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/e/apply-electric-circuits-and-ohm-s-law 2026-06-29T18:00:57.756067884Z Apply: Electric circuits and Ohm's law Apply your understanding of electric circuits and Ohm's law in this set of free, standards-aligned practice questions. Emily Cizmas exercise https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/e/voltage-and-ohm-s-law-ap1 2026-06-09T01:30:45.805316646Z Applying Ohm's law Practice using Ohm's law to predict changes in electric potential difference, resistance, or current for a circuit component.  April Russell exercise https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/resistivity-and-conductivity 2023-09-10T17:11:17.624018169Z Resistivity and conductivity Let's look at the properties of materials that cause a resistor to resist the flow of current. Explore the principles of Ohm's law, resistance, and resistivity in electrical circuits. Understand how resistance is defined by voltage and current, and how it remains constant in Ohmic materials. Discover the factors that influence resistance, including the length, cross-sectional area, and material of a resistor. David SantoPietro video https://cdn.kastatic.org/googleusercontent/-RlW8oVnlZWWOXxxRFGIP8eQTs9MZL5s5D8ukkvjimXnLYaLbIYOgBrIyt0QZKF69KItib1LU4Ie6iVJcPr2iA_B Resistivity and conductivity Let's look at the properties of materials that cause a resistor to resist the flow of current. Explore the principles of Ohm's law, resistance, and resistivity in electrical circuits. Understand how resistance is defined by voltage and current, and how it remains constant in Ohmic materials. Discover the factors that influence resistance, including the length, cross-sectional area, and material of a resistor. https://cdn.kastatic.org/ka-youtube-converted/4rsswT_Rv1M.mp4/4rsswT_Rv1M.mp4 722 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/ee-kirchhoffs-current-law 2021-02-22T19:49:34Z Kirchhoff's current law Kirchhoff's Current Law says the currents flowing into a node must add up to zero. Willy McAllister video https://cdn.kastatic.org/googleusercontent/V845j2s6nZJ4klE3t-zRWKCmXNWcmAwT_4BugrDlgltyVzve2MCzjCqeKkrvK7sqxpFr-GMd2qQ1gBep03-E9kzl Kirchhoff's current law Kirchhoff's Current Law says the currents flowing into a node must add up to zero. https://cdn.kastatic.org/ka-youtube-converted/OYerdzZPSI0.mp4/OYerdzZPSI0.mp4 363 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/ee-kirchhoffs-voltage-law 2021-02-22T19:49:33Z Kirchhoff's voltage law Kirchhoff's Voltage Law says if you travel around any loop in a circuit, the voltages across the elements add up to zero. Willy McAllister video https://cdn.kastatic.org/googleusercontent/YmeBi0ngxmr1s_QkA4WhTmU5GQ7PwV6N1giU7arJWCu9CJX02987w4bsLSguUecjDfzjUfYkVgiOUar_zIhqIDM Kirchhoff's voltage law Kirchhoff's Voltage Law says if you travel around any loop in a circuit, the voltages across the elements add up to zero. https://cdn.kastatic.org/ka-youtube-converted/Bt6V7D5av9A.mp4/Bt6V7D5av9A.mp4 410 Circuits, Ohm's law, and Kirchhoff's laws https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/a/ee-kirchhoffs-laws 2026-07-02T04:40:35.242673419Z Learn and try: Kirchhoff's laws Kirchhoff's Laws describe current in a node and voltage around a loop. These two laws are the foundation of advanced circuit analysis. article https://www.khanacademy.org/science/ap-physics-2/x0e2f5a2c:electric-circuits/x0e2f5a2c:circuits-oms-kirchhoffs-laws/v/electric-power 2021-02-07T17:14:01Z Electric power In this video David derives the formula to find the power used by a resistor. David SantoPietro video https://cdn.kastatic.org/googleusercontent/psrWwmdyil3NK5TgZha2voCapkkugfOi4Whifsj114iu3M2vK8MtrcSB8Izr0Tm_atxfY_ViR9s-88P_i5j-SLdx Electric power In this video David derives the formula to find the power used by a resistor. https://cdn.kastatic.org/ka-youtube-converted/3zt7DWUiaDE.mp4/3zt7DWUiaDE.mp4 643 Circuits, Ohm's law, and Kirchhoff's laws