IIT-JEE-Physics-Screening–2001

SCREENING 
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1. Three positive charges of equal value q are placed at the vertices of an equilateral triangle. The resulting lines of force should ne sketched as in : 

 

2. When a block of iron floats in mercury at 00C, a fraction k1 of its volume is submerged, while at the temperature 600 C, a fraction k2 is seen to be submerged. If the coefficient of volume expansion of iron γFe and that of mercury is γHg, then the ratio k1 / k2 can be expressed as : 
(A) (1+60 γFe )/(1+ 60 γHg ) 
(B) (1-60 γFe )/(1+ 60 γHg ) 
(C) (1+60 γFe )/(1- 60 γHg ) 
(D) (1+60 γHg )/(1+ 60 γFe ) 

3. Three rods made of the same material and having the same cross-section have been joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at 00C and 900C respectively. The temperature of the junction of the three rods will be: 

                          
(A) 450C
(B) 600C 
(C) 300C
(D) 200C 

4. In a given process of an ideal gas, dW = 0 and dQ <0.Then for the gas : 
(A) The temperature will decrease 
(B) The volume will increase 
(C) The pressure will remain constant 
(D) The temperature will increase 

5. The electron emitted in beta radiation originates from :
(A) Inner orbits of atoms 
(B) Free electrons existing in nuclei 
(C) Decay of a neutron in a nucleus 
(D) Photon escaping from the nucleus 

6. The transition from the state n = 4 to n =3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition : 
(A) 2→1
(B) 3→2
(C) 4→2
(D) 5→4

7. In the given circuit with steady current the potential drop across the capacitor must be : 

                    
(A) V
(B) V/2
(C) V/3
(D) 2V/3

8. The intensity of X- Rays from a Coolidge tube is plotted against wavelength λ as shown in the figure. The minimum wavelength found is λC and the wavelength of the kC line is λK. As the accelerating voltage is increased : 

                                  
(A) λK – λC increases 
(B) λK – λC decreases 
(C) λK increases 
(D) λK decreases 

9. Two beams of light having intensities I and 4 I interfere to produce a fringe pattern on a screen. The phase difference between the beans is π/2at point A and π at point B. Then the difference between the resultant intensities at A and B is : 
(A) 2 I 
(B) 4 I 
(C) 5 I 
(D) 7 I

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