09/6/25
Vector and scalar quantities:
A vector quantity has magnitude and direction.
A Scalar has only magnitude.
How to draw a scale diagram
10/6/25
What is radiation
The emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles, which cause ionization.
Potential and kinetic energy:
Potential energy is the stored energy within a system depending on an object's position.
Kinetic energy is the energy an object possesses due to its motion.
11/6/25
Specific heat capacity is the amount of energy required to increase the temperature of 1 kg of an object by 1 degree Celsius.
Specific heat capacity = change in energy/(mass * change in temperature)
Refractive index is the speed of light in a vacuum/ speed of light in a medium.
Formula: n = c * v
12/6/25
Focal length:
The focal point is basically the diameter of a lens (the complete circle of a lens)
Refractive index is basically the difference in density of a medium and the speed of light in a different medium.
A convex lens converges the light rays, a Concave lens diverges the light rays, Refraction depends upon the angle, no angle = no refraction.
13/6/25 and 14/6/25
-A longitudinal wave is a wave where particle displacement is parallel to the direction of propagation.
-A transverse wave is a motion in which all points on a wave oscillate along paths at right angles to the direction of the wave's advance.
Question: Why does water move as a wave when there is a disturbance?
Ans: The water molecules share the energy given by the disturbence in the form of a wave, since there is a medium for the wave to travel across, (water waves are not fully transverse, they are a mix of transverse and longitudanal waves) The water molecules move back and forth sharing their energy to the next molecules, and the high points in the water wave is the compression and the low point is the rarefraction (if you look at it like a longitudanal wave) or the hight point is the crest and the lowest is the trough. Crest has the molecules vibrating with all the energy, and trough has all the molecules going back to their original position after sharing the energy.
21/6/25
A resistor is an electronic component that resists or limits the flow of electric current in a circuit. Think of it like a narrow pipe in a water system — it controls how much water (current) flows through.
Current Flow: When electric current tries to pass through a resistor, the resistor opposes it.
Heat: Some electrical energy is converted into heat due to this opposition.
Resistors are important in electronics because they:
Control Current: Prevent too much current from damaging sensitive components.
Divide Voltage: Create specific voltage levels for different parts of a circuit.
Protect Components: Limit current to protect LEDs, transistors, microchips, etc.
Set Timing: Work with capacitors in timing circuits (like in clocks, alarms).
Filter Signals: Used in filters and amplifiers in audio and communication circuits.
Fixed Resistors
These have a constant value of resistance.
Examples:
Carbon Composition Resistors
Made of carbon powder & binder.
Cheap, used in old circuits.
Metal Film Resistors
More accurate & stable.
Common in modern circuits.
Wire Wound Resistors
Made by winding wire (usually nichrome).
Handle high power & heat.
Variable Resistors
You can change their resistance value.
Examples:
Potentiometers (Pots):
Three terminals, like a volume knob.
Rheostats:
Two terminals, used to adjust current.
Trimmers:
Small adjustable resistors, used for fine-tuning.
Special Resistors
- Thermistors (Temperature Sensitive)
Resistance changes with temperature.
Types:
NTC (Negative Temperature Coefficient): Resistance decreases as temp increases.
PTC (Positive Temperature Coefficient): Resistance increases as temp increases.
Used in temperature sensors, circuits protection.
- LDR (Light Dependent Resistor)
Resistance changes with light.
Used in automatic lights, night lamps.
- Varistors (Voltage Dependent Resistor)
Resistance changes with voltage.
Used for surge protection.
