Monday, April 30, 2012

CBSE PHYSICS: X MCQ On Electricity

            (Practice) MCQ of Electricity
1.Electricity constituted by electric charges at rest on the surface of a conductor is called
a. Electricity b. Potential difference c. Current electricity d. Static electricity
 2.The closed path between two points at different potentials, to make the electric current flow is called
a. Electric circuit b. Electric current   c. Electric potential d. Electric cell.
3. Direction of conventional current is taken from a. Negative to positive b. Positive to negative
c. It could be from positive to negative or negative to positive d. None of these.
4. With increase in temperature, resistance of a conductor
 a. Decreases                                                      b. Increases      
c . May decreases or increases depending on temperature  
d. It does not depend on temperature.
5. In series combination, resistance increases due to increase in
a. Temperature b Humidity c. Length d. Area of cross-section.
6. In parallel combination, resistance decreases due to increase in
a. Temperature     b. Humidity c.  Area of cross-section  d. Length.
7. The rate at which electricity is dissipated or consumed by an appliance is called electrical
a. current b. Power c. Potential d. Energy.
8. The unit of electrical power is
a. watt b. ampere c. joule d. ohm.
9. In series combination of electrical appliances, total electrical power
a. Increases b. Decreases  c. May increases or decreases d. Does not changes.
20.The equivalent resistance in series combination is
a. Smaller than the resistance having high value
b .Larger than the largest resistance
c. Smaller than the smallest resistance
d. Larger than the smallest resistance.
21.In a circuit containing two unequal resistors connected in parallel
a. The current is same in both resistors
b. The current is large in the resistance having more value  
c. The voltage is same across both the resistors  
d .The voltage drops is larger across both the resistors.
22.. A fuse wire is always inserted in the
a. Live wire b. In the neutral wire c. In the earth wire d. May be connected in any line.
23. Two bulbs in a house, one glow brighter than the other. The bulb with large resistance is
a. Dim bulb b. The brighter bulb c. Both has same resistance d. None of these.
24.The characteristics of fuse wire is
a. High melting point                                    b Low melting point
c. Low  resistivity  and high melting point      d. High resistivity and low melting point.
25.The unit of specific resistance is
A .Ohm/m2 b. Ohm-m c. Ohm m3 d. Ohm/m3
ANSWERS :     Q1.d        Q2.a          Q3.b          Q4.b             Q5.c      Q6.c   Q7.b       Q8.a
Q9.b         Q10.a           Q11c.   12.b    Q13.b      Q14.b        Q15.b        Q16.c         Q17.b  
Q18.b   Q19.c        Q20.b       Q21.c         Q22.a        Q23.a   Q24.d   Q25.b

Saturday, April 28, 2012

CBSE PHYSICS: CBSE X Current Electricity Worksheet

CBSE PHYSICS: CBSE X Current Electricity Worksheet: Chapter: Current Electricity Worksheet          By Jsunil Tutorial  1. Define electric current, state its unit, list the equation defining...

CBSE PHYSICS

Monday, April 16, 2012

CBSE PHYSICS: Force Fiction and Pressure for VIII Physics-Notes a...

FORCE AND PRESSURE
A force is a push or pulls acting on an object which changes or tends to change the state of the object.
In the international system of units (SI System), the unit of force is Newton (N) that is named after Sir Isaac Newton.

There are also other units like dyne, kilogram weight and pound.

Action of force and its effects: 

Contact and non-contact forces

A force forces which act only when there is physical contact between two interacting objects are known as contact forces. 

Forces which can act without physical contact between objects, i.e. those that can act from a distance, are called non-contact forces or field forces.

Types of forces

1. Muscular force: This is the force we can exert with our bodies by using our muscles, e.g. pull, push, kick etc. These are contact forces

2. Magnetic force : Magnets exert forces of attraction or repulsion on other magnets. An important feature of magnetic force is that it can act from a distance, and is therefore of a non-contact force.

3. Electrostatic force: The force exerted by a charged body on another charged or uncharged body is known as electrostatic force. Electrostatic force is used to separate solid pollutant particles from smoke given out from factories.

4. Gravitational force : All objects in the universe exert a force on all other objects. This is called gravitational force. The  gravitational force exerted by the Earth on all the bodies on its surface is called gravity.

5. Frictional force : The fact that the rolling ball comes to rest after some time shows that there must be a force acting on it which tends to slow it down. This force seems to be more on rough surfaces than on smooth surfaces. The force acting against the relative motion of surfaces in contact is called frictional force or friction.

6. Tension Force:Strings, ropes and chains can only pull on things!  The force of pull supplied by strings, ropes or chains is called the tension force. The tension force is always directed along the length of the thing doing the pulling (string, rope, chain).

7. Spring Force‎: is the force exerted by a compressed or stretched spring upon any object that is attached to it.

8. Applied Force:  An applied force is a force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object. The applied force is the force exerted on the desk by the person.

Mass and Weight : The mass of an object is the amount of matter that is contained by the object; the weight of an object is the force of gravity acting upon that object.
The mass of an object (measured in kg) by Pan Balance and  will be the same no matter where in the universe that object is located. On the other hand, the weight of an object (measured in Newton) by Spring balance and  will vary according to where in the universe the object is

Type of friction:

CBSE PHYSICS: Fore Fiction and Pressure for VIII Physics-Notes Click Here