Physics

• The SI (Standard International) unit system is the most widely used system in measurement and comprises seven fundamental units.
• There is no force on BC because the magnetic flux must be perpendicular to the current.
• Passing a magnet along a solenoid can allow electron flow and thus produce a voltage, as per Faraday’s Law.
• The direction of the wire in Fig 1 is downwards.
• An arrow indicating the conventional current direction, as well as the +ve and – ve terminals should be drawn.
• The purpose of the d.c motor is to create a moment on both sides of the wire loops to create a turning force.
• Instead of a commutator, slip rings are placed at the end of the wire loop in an a.c generator to allow the transfer of the alternating e.m.f induced by the rotating wire to the external circuit.
• The voltage (or emf) induced in a coil is proportional to the rate of magnetic force across it.
• A sensitive galvanometer is necessary to detect very small changes in current.
• Force, magnetic field and current are linked this way.
• If two are at a right angle, the third can be produced.
• The direction of the turning force depends on the orientation of the magnets and direction of conventional current.
• Fleming’s Left Hand Rule is used to predict the force, magnetic field and direction caused by a passing current.
• The coil ABCD will have a clockwise or anticlockwise moment by determining the forces on AB and CD.
• In order for this interaction to occur, all three must be perpendicular to each other.
• In Fig 2, the wire is being thrusted out of the page.
• A driver received a ticket while going 24m/s on a 80 km/h road, did he exceed the speed limit?
• The mass in u is converted to kilograms by multiplying by 1.66 x 10 -27.
• The speed of light is estimated as 3.0 x 10 8 m/s.
• A Boeing 747 jet experiences a lift velocity of 125m/s while travelling horizontally on the runway at 175m/s, with an angle between the lift and the runway of 60 o.
• The two figures show a plane going north and being affected by a wind blowing in different directions at a magnitude of 30 km/h.
• The distance it takes for light to travel in one year, a light year, is calculated as distance = speed x time, where speed is the speed of light and time is 365 days.
• The difference in masses, Δm, is calculated as 5.03 - 5.012 = 0.018 u.
• The energy released in the reaction, ΔE, is calculated as Δmc 2 = (2.988 x 10 -29) x (9 x 10 16).
• The speed limit on Trinidad’s highways is 100km/h, which can be converted to m/s.
• The mass on the left side of the equation is calculated as H-2 + H-3 = 2.014 + 3.016 = 5.03 u, while the right side of the equation is calculated as He + n = 4.003 + 1.009 = 5.012 u.
• The difference in mass was converted to energy according to Einstein.
• If voltage is raised (step-up transformer), it trades by lowering the current.
• In an IDEAL transformer, power input and output are said to be equal.
• The following formulas are used in transformers: Calculate the number of secondary coils and the secondary current in the primary coil.
• To minimize power loss across a wire, electrical energy is transferred with high voltages and low currents.
• Power loss does occur in transformers in real-world.
• The more coils, the greater the electron flow and the higher the voltage.
• An electric kettle is connected to an alarm that sounds whenever the kettle is switched on and the lid is left open or the water level is below the heating element.
• Due to the principle of conservation of energy, the power and energy output can never be more than the input.
• There are numerous ways in which power loss can occur in a transformer, stated below: Line loss (heating) Using wires of greater diameter Eddy currents Laminating the soft iron core Hysteresis (delay during magnetization) Using a perm-alloy core
• The following logic gates are used in circuits: NOT, AND, OR, NAND, NOR.
• A transformer uses the concept of a constantly changing magnetic field to induce a voltage from a primary to secondary coil.
• If voltage is lowered (step-down transformer), current is raised.
• The circuit that controls the electric kettle’s alarm includes logic gates A, B, and C.