Question
Artificial radioactivity was discovered by:
✓
Answer
- Irene Curie and Joliot.
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A moving charge produces :
A block $A$ kept on an inclined surface just begins to slide if the inclination is $30^\circ$ . The block is replaced by another block $B$ and it is found that it just begins to slide if the inclination is $40^\circ$ :
→- Mass of $A >$ mass of $ B$.
- Mass of $A <$ mass of $B$.
- Mass of $A =$ mass of $B.$
- All the three are possible.
The energy band gap is maximum in (a) Metals(b) Superconductors(c) Insulators(d) Semiconductors
The impedance of a series L - C - R circuit in an AC circuit is.
The number of dry cells, each of e.m.f. 1.5 volt and internal resistance 0.5 ohm that must be joined in series with a resistance of 20 ohm so as to send a current of 0.6 ampere through the circuit is(a) 2 (b) 8(c) 10 (d) 12
The X-ray beam emerging from an X-ray tube:
The process of radioactive radiations remains unaffected due to:
Assertion : A bar magnet is dropped into a long vertical copper tube. Even taking air resistance as negligible, the magnet attains a constant terminal velocity. If the tube is heated, the terminal velocity gets increased.
Reason : The terminal velocity depends on eddy current produced in bar magnet.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.
Reason : The terminal velocity depends on eddy current produced in bar magnet.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.
In a circuit inductance $L$ and capacitance $C$ are connected as shown in figure. $A_{1}$ and $A_2$ are ammeters.
When key $K$ is pressed to complete the circuit, then just after closing key $(K),$ the readings of $A_{1 }$ and $A_2$ will be.
→When key $K$ is pressed to complete the circuit, then just after closing key $(K),$ the readings of $A_{1 }$ and $A_2$ will be.
According to Mosley's law, the frequency of a spectral line in X-ray spectrum varies as(a) Atomic number of the element(b) Square of the atomic number of the element(c) Square root of the atomic number of the element(d) Fourth power of the atomic number of the element