# CONFIRM 2012 NECO PRATICAL SOLUTION.

Filed in Uncategorized by on June 10, 2012

PHYSICS PRACTICAL SOLUTION: 1.

Suspend a meter rule horizontally on the knife edge supplied.

Adjust the meter rule carefully until it settler horizontally.

Repeat and record the point of balance G of the meter rule.

Keep the knife edge at the point G throughout the experiment.

Suspend the object labelled Q at the 20cm mark of the meter rule.

On the other side of G, suspend the mass M= 10g and adjust its position until the meter rule settler horizontally.

Read off the position R of the mass M on the meter rule.

Record the distance y between G and R. Also, record the value of M.

Repeat the procedure keeping the knife edge at G and the object Q at the 20cm mark but using the masses M, 10,20,30 and 40g On the other side of G.

In each case, record the distance y and corresponding value of M.

Plot a graph of m against 1/y.

Determine the the slope of the graph.

Evaluate s/x. State two Precautions. Explain what is meant by the center of gravity of a body.

State how this is related to the stability of the body.

SOLUTION: TABLE:

S/N|M(g)|y(cm)|1/y(cm^-1)

1. |10.00 |56.40 |0.0189

2. |20.00 |52.68 |0.019 3. |30.00 |35.12 |0.028

4. |40.00 |26.34 |0.038

5. |50.00 |21.07 |0.047

PRECAUTIONS:

=1. I ensured the reading was taking when my meter rule is balanced.

=2. I avoided Parallex error.

Bi) The center of gravity of a body is the point at which the resultant weight of the body appears to act.

QUESTION 2.

Using the diagram as a guide, carry out the following instructions.

(i) Place the pin,O, horizontally inside the cylinder provided.

Pour some water on the pin in the cylinder such that the length of the water column, l = SO = 10.0cm.

Where S represent the water meniscus.

(ii) Insert another pin P in the cork help by the boss of the retort stand.

(iii) Adjust the position of P vertically upward or O formed by refraction at S.

(iv) Read and Record the distance h = PO.

(v) Repeat the procedure for four other values of I = 15, 20, 25 and 30cm.

(vi) In each case, measure and record the corresponding value of h.

(vii). Plot a graph of h on the vertical axis against I on the horizontal axis.

(viii)Determine the slope S of the graph.

(ix) Evaluate

(a)K1= I-S

(b)K2=1/k

(x) State two precautions taken to ensure accurate result.

(Bi) Explain total Internal reflection of light.

(ii) A rectangular glass prism of thickness 6cm and refractive index 1.5 is placed on the page of a book.

The prints on the book are viewed vertically downwards from above.

Determine the apparent upward displacement of this prints.

SOLUTION:

TABLE OF VALUES:

S/N| Icm^3| h(cm3)

1. | 10.00 | 7.50

2. | 15.00 | 11.25

3. | 20.00 | 15.00

4. | 25.00 | 18.75

5. | 30.00 | 22.50 (x)

PRECAUTIONS

1. The lower level of meniscus of water is read at eye level.

2. I avoided error due to parallex.

3. Zero error of meter rule is noted.

(Bi) Total internal reflection occurs when light travel from a dense medium to a less dense medium such that angle of incidence is greater than critical angle.

(ii) Let the apparent upward displacement of points b t, real depth, D = 6cm.

Therefore apparent depth = D – t = 6 – t Refractive index aÑg = 1.5 =Realdepth/Apparent depth. 1.5=6/6-t (6-t)1.5=6cm 9-1.5t=6 -1.5t=6-9 t=6 – 9/2.0cm R.I = R.D/A.D .A.D = R.D/R.I = 6/1.5 = 4cm.

Displacement = Realdepth – Apparent depth = 6-4=2.0cm