Shah Jamal 
Ohm’s law states that the current through a conductor between two points is directly proportional to the potential difference across the two points. Introducing the constant of proportionality, the resistance,[1] one arrives at the usual mathematical equation that describes this relationship: where I is the current through the conductor in … Read more
Refraction is the change in direction of a wave due to a change in speed at the boundary between two media of different density. The Latin word “fract” in refraction means to break. Refraction is the “breaking or bending” of waves as it travels to a different density media. The absolute index of refraction of … Read more
A vibrating sample magnetometer or VSM is a scientific instrument that measures magnetic properties, invented in 1955 by Simon Foner at Lincoln Laboratory MIT. The paper about his work was published shortly afterward in 1959[1] A sample is placed inside a uniform magnetic field to magnetize the sample. The sample is then physically vibrated sinusoidally, … Read more
A practical electrical power source which is a linear electric circuit may, according to Thévenin’s theorem, be represented as an ideal voltage source in series with an impedance. This resistance is termed the internal resistance of the source. When the power source delivers current, the measured e.m.f. (voltage output) is lower than the no-load voltage; … Read more
Concave mirror: A concave mirror diagram showing the focus, focal length, centre of curvature, principal axis, etc. A concave mirror, or converging mirror, has a reflecting surface that bulges inward (away from the incident light). Concave mirrors reflect light inward to one focal point.They are used to focus light. Unlike convex mirrors, concave mirrors show … Read more
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long … Read more
A potentiometer measuring instrument is essentially a voltage divider used for measuring electric potential (voltage); the component is an implementation of the same principle, hence its name. Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a mechanism can be used as position transducers, for example, … Read more
Class One NCTB Book 2018 Download. National Curriculum and Textbook Board (NCTB) has published new year’s Textbooks for class 1. These classes comprise primary education in Bangladesh as well as rest of the world. The Book has not been changed from 2013 Text Book of Class I All PDF National Curriculum & Textbook Board Bangladesh Class … Read more
Class Two NCTB Book 2018 Download. National Curriculum and Textbook Board (NCTB) has published new year’s Textbooks for class 2. These classes comprise primary education in Bangladesh as well as rest of the world. The Book has not been changed from 2013 Text Book of Class II All PDF National Curriculum & Textbook Board Bangladesh Class … Read more
