What causes humming in thermos flasks?                          124
What is the advantage of an electric locomotive over
  the steam one?                                                125
How does an electric train work?                                126
What considerations determine how many blades a fan has?
  How does the number of blades affect the amount and 
  velocity of the air it moves? And, as an aside, are the
  underwater propellers that are used for moving boats
  and ships subject to the same considerations?                 126
Why is resolution of satellite images termed in meters?         127
How does one control the movement of hot air balloons?          128
Is it true that TV, fridge and other electrical and electronic
  gadgets should not be switched on immediately after
  switching off?                                                128
Why is the capacity of the refrigerator indicated in litres?
  How is it measured?                                           129
How do microwave ovens work?                                    130
Can we use a TV monitor for a computer monitor and the
  vice versa?                                                   131
Why is it that a room illuminated by a television
  appears blue to an outside viewer regardless of the 
  colours that are being displayed on the screen?               132
When a vehicle crosses the road some flickering may be
  noticed on the television screen. Why does the 
  flickering occur?                                             132
What is the black stripe bordering a colour TV screen?          133
How does remote control in TV work?                             134
How does lightning affect TVs?                                  134
How does a dish antenna receive signals?                        135
Why do metals shine?                                            136
What is superconductivity?                                      137
Why does the grid fail when excessive power is
  drawn from it?                                                138
How is electricity produced from nuclear materials?             140
How does electric current cause death?                          141
Why is the voltage of electric power always given in 
  multiples of 11 such as 110V, 220V, 440V and 11 kV?           141
What will be the speed variation when a single phase
  4800 RPM, HP, 60 Hz, 220 volts motor is made to run
  on a single phase 50 Hz, 220 volts supply?                    
  Will it burn out or get overheated? Is it safe to run
  on a continuous basis giving load to it?                      142
Why is it easier to pull than to push a lawn roller?            143
What is Indian driving cycle? What is the procedure
  adopted for it?                                               145
What is the principle of photo-chromatic glasses?               146
How does a sim card function in a cellphone?                    147
How does an exhaust silencer work?                              148
How does airbrake differ from the hydraulic?                    149
How are optical fibres different from ordinary cables?          151
Who is a ham?                                                   152
What is the difference between the working systems of
  fax and telegram?                                             153
What are the exclusive properties of silicon that have 
  enabled its usage in electronics?                             155
What are T-rays?                                                156
What is the difference between radar and sonar?                 158
What is plasma emission spectroscopy?                           159
In what way are spatial sound, wide sound and surround
  sound different from stereo sound?                            161
What is the science behind the swing of a cricket ball?         162
Why does a steel ball pitch higher than a rubber ball?          165
What is fourth dimension? What does it explain?                 166
Why does a diamond sparkle more than a glass imitation
  cut to the same shape?                                        167
How does a compact fluorescent lamp consume less
  electricity than conventional fluorescent lamps and bulbs?    168
Unlike fluorescent light, why does sunlight produce
  sharper shadows?                                              169
What is magnetic levitation? How does it work?                  171
How is mass different from weight?                              172
Can we receive a mobile signal while travelling in 
  an aeroplane?                                                 173
How does an image change in a 3-D hologram depending 
  on angle of viewing?                                          175
How does a photo chromatic glass turn dark when 
  exposed to sunlight?                                          176
Why is the power of a loudspeaker expressed in watts?           176
How does a lightning arrestor work?                             176
What are polaroid sunglasses made of?                           178
When a bullet is fired from a gun, the bullet revolves
  around itself while moving. Why does it happen?               179
How do touch screens work?                                      180
Why doe we feel a pulling sensation when we stand near
  a running train?                                              182
Why are diesel driven vehicles noisy?                           182
How are helicopters able to hover in the air?                   183
Nobel Laureates in Physics                                      185