Scientific learning

 Scientific Study

The scientific method is the process of objectively establishing facts through testing and experimentation. The basic process involves making an observation, forming a hypothesis, making a prediction, conducting an experiment and finally analyzing the results. The principals of the scientific method can be applied in many areas, including scientific research, business and technology.

Variables in Scientific Study

As we know scientific study involve process of observation and experimentation, we need to consider some physical quantities that we observe , manipulate or keep consant during our study. Those measurable quantities are called Variables. 

Types of Variables

• Independent Variable
• Dependent Variable
• Control Variable

Example 1.1

Let us consider an experiment in which we are studying the effect on growth of plant with the use of fertilizer.

• Here We are observing the "growth of plant" so it is dependent variable.
• In this experiment we study the " growth of plant by changing the amount of "fertilizer" so it is dependent variable.
• The growth of plant also depends upon other factors also like type of seed, amount of water, type of soil etc. So while studying the effect of fertilizer (independent variable), we keep those varables constant. Such variables are called control variable.

Independent Variable

An independent variable is the variable we manipulate or vary in an experimental study to explore its effects. It’s called “independent” because it’s not influenced by any other variables in the study.

Dependent Variable

A dependent variable is the variable that changes as a result of the change in independent variable. It is what we are  interested to study, and it “depends” on  independent variable.

Experiment / problem	Independent variable	Dependent variable(s)
Do tomatoes grow fastest under fluorescent, incandescent, or natural light?	Type of light the tomato plant is grown under	The rate of growth of the tomato plant
What is the effect of intermittent fasting on blood sugar levels?	Presence or absence of intermittent fasting	Blood sugar levels
Is medical marijuana effective for pain reduction in people with chronic pain?	Presence or absence of medical marijuana use	Frequency of pain Intensity of pain
To what extent does remote working increase job satisfaction?	Type of work environment (remote or in office)	Job satisfaction self-reports

Difference Between Dependent and Independent Variable

Independent Variable	Dependent Variable
An Independent variable is a variable whose value never depends on another variable.	A dependent variable is a variable whose value depends on another variable.
The Independent variable is the presumed cause.	The dependent variable is the presumed effect.
Any change in the independent variable also affects the dependent variable.	Dependent variable changes, then the independent variable will not be affected.
Independent variables are the predictors or regressors.	Dependent variables are often referred as the predicted variable.
Independent variables can become easily obtainable and do not need any complex mathematical procedures and observations.	Dependent variables are obtained from longitudinal research or by solving complex mathematical equations.
Independent variables are can be manipulated by the researcher. So he or she is biased. Then it may affect the results of the research.	You cannot be manipulated by the research or any other external factor.
Independent variables are positioned horizontally on the graph.	Dependent variables are positioned vertically on the graph.

Control Variable

A control variable is anything that is held constant or limited in a research study. It’s a variable that is not of interest to the study’s objectives, but is controlled because it could influence the outcomes.

Points to be considered in variables

1. In an experiment or research there must a single independent variable.
2. In an experiment or research there must be a single dependent variable.
3. All other variables except dependent and independent variables must be kept constant.
4. While writing variables in the form of mathematical equation, independent variable should be on right side and dependent variable on left. e.g 
   s = vt    ( s ∝ t)
   we are studying the distance covered by a vehicle in different time keeping the velocity constant. 
   so, t= independent variable
        s = dependent variable
        v = control variable
5. In a graph independent varaible is always in x- axis and dependent variable is always in y axis. So a graph shows the variation of dependent variable (x-axis ) with change in independent variable (y-axis).
   
   
   
6. 
   

New Model Question XII

Comp. English

Comp. Nepali

Comp. Social Studies

Comp Mathematics

Physics                                                                          Account 'A'

Biology                                                                         Account 'B'

Chemistry                                                                     Economics

                                                                                      Finance

                                 Computer

Physics Model Question 1

 

CLASS:12 SUBJECT: PHYSICS

FM: 75 TIME: 3Hrs

GROUP-A

Attempt all questions (11x1=11)

1.       A SHM has a amplitude A and time period T. The time taken by it to travel from x= A to x= A/2 is;

(a)                  T/12 (b) T/3 (c) T/4 (d) T/6

2.       A liquid is flowing in a tube under streamline flow. If the radius of the tube is doubled , the rate flow becomes;

(a)   Four times (b) 16 times (c) 2 times (d) ¼ times

3.       15g of air is heated from 0⁰C to 5⁰C at constant volume by adding 150cal of heat. The change in internal energy per gram is;

(a)   150cal (b) 10cal (c) 750cal (d) 180cal

4.       The distance between two consecutive antinodes is 0.5m. The distance travelled by the wave half the time period is;

(a)   0.25m (b)0.5m (c)1m (d) 2m

5.       Young’s double slit experiment confirms that;

(a)   Light is source of energy (b) Particle nature of light
(c) wave nature of light (d) None of all

6.       Which of the following is the most important factor that helps to recognize a person by his voice?

(a)                  Intensity (b) pitch (c) quality (d) None of all

7.       Seebeck effect helps to determine;

(a)   Direction of current (c) magnitude of emf

(b)  Nature of material (d) all of above

8.       Magnetic field inside the solenoid is independent of;

(a)                  Length of solenoid (c) radius of solenoid

(b)     Number of turns in solenoid (d) current in solenoid

9.       An electron and proton are under the effect of same electric field. They will experience;

(a)     Same force and same acceleration

(b)     Same force and different acceleration

(c)     Different force and same acceleration

(d)     Different force and different acceleration

10.    The unit of inductance is;

(a) V/m b) J/A c) VsA^-1 d)VA

11.    Which gate is an inverter gate?

(a)NOT gate (b) OR gate c) AND gate d) none

GROUP-B

Attempt all questions[8x5=40]

1.     (a) In a physics lab, you attach a 0.200 kg air-track glider to the end of an ideal spring of negligible mass and start it oscillating. The elapsed time from when the glider first moves through the equilibrium point to the second time it moves through that point is 2.60 s. Find the spring’s force constant[3]

b) At what point in the motion of a simple pendulum is the string tension greatest? Least?[2]

2.       (a)What is molecular theory of surface tension.[3]

(b).The ship rides several centimeters lower in the water in lake than it did in the ocean. Explain.[2]

3.       (a)Derive the Poisseulle’s formula[3]

(b).How can you distinguish the laminar flow of fluid with turbulent flow?[2]

4.       (a)What is molecular theory of surface tension.[3]

(b).The ship rides several centimeters lower in the water in lake than it did in the ocean. Explain.[2]

5.       What is the Wheatstone bridge? Find the balanced condition of Wheatstone’s by using Kirchoff’s laws[1+4=5]

6.       (a)How did Laplace corrected Newton’s formula for velocity of sound?[3]

(b) Calculate the speed of sound in air at 20⁰C if density of air is 1.29kg/m³, molar mass 28.8g and pressure 1.1013 x10⁴Pa (γ for air is 1.4)[2]

7.       (a)Define the coherent sources of light[1]

(b).Prove analytically that the bright and dark fringes in Young’s double slit experiment are equally spaced.{No necessary for full derivation}[2]

(C) define the closed organ pipe and hence define the resonance condition for the stationary wave formation[2]

OR

Describe the different modes of stationary wave produced in the closed organ pipe[3]

What is end correction of organ pipe[2]

8.       (a)How the electrons are emitted from metal surface in the photoelectric effect?[2]

(b).Derive the Einstein’s photoelectric equation[3]

OR

What are rectifiers? [1]

How the filter circuit added to rectifier can make uniform output voltage.[2.]

Write the forward bias characteristics of PN junction diode.[2]

GROUP-C

Attempt all questions[3x8=24]

1.       (a) What is the use of Biot and Savart’s law?[1]

(b) Describe how the Hall voltage is developed during Hall effect.[2]

(c) What is Ampere’s circuital law[2]

(d) Use Ampere’s law to determine the magnetic field due to solenoid.[3]

OR

(a)Define electromagnetic induction.[1]

(b)What is Lenz law ? How does it follow the law of conservation of energy[3]

(c) Describe about the working of potentiometer and hence write the expression of internal resistance of given cell with use of potentiometer

 

 

 

 

2. (a) A machinist is using a wrench to loosen a nut. The wrench is 25.0 cm long, and he exerts a 17.0 N force at the end of the handle at 37° with the handle . (i) What torque does the machinist exert about the center of the nut? (ii) What is the maximum torque he could exert with a force of this magnitude, and how should the force be oriented?[2+3=5]

(b)Derive the expression of acceleration of body rolling down an inclined plane[3]

3. What are Bohr’s postulates for hydrogen like atom? Hence find the expression of radius of nth orbit, velocity of electron and total energy of electron in that orbit by using the Bohr’s postulates.[3+1.5+1+2.5]

 

 

 

 

Sample Research Report

 

Sample Research proposal

 

SEE Science New Model Question 2079