The scientist who discovered the two elements radium and polonium would be Marie Curie in 1898.
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1. 
Explanation:
We have:
voltage in the primary coil
voltage in the secondary coil
The efficiency of the transformer is 100%: this means that the power in the primary coil and in the secondary coil are equal

where I1 and I2 are the currents in the two coils. Re-arranging the equation, we find

which means that the current in the secondary coil is 14% of the value of the current in the primary coil.
2. 5.7 V
We can solve the problem by using the transformer equation:

where:
Np = 400 is the number of turns in the primary coil
Ns = 19 is the number of turns in the secondary coil
Vp = 120 V is the voltage in the primary coil
Vs = ? is the voltage in the secondary coil
Re-arranging the formula and substituting the numbers, we find:

Answer:
Final temperature of the aluminum = 41.8 °C
Explanation:
We have the equation for energy
E = mcΔT
Here m = 55 g = 0.055 kg
ΔT = T - 27.5
Specific heat capacity of aluminum = 921.096 J/kg.K
E = 725 J
Substituting
E = mcΔT
725 = 0.055 x 921.096 x (T - 27.5)
T - 27.5 = 14.31
T = 41.81 ° C = 41.8 °C
Final temperature of the aluminum = 41.8 °C
Answer: C Plane
Explanation: According to Newton's law, gravitational force is proportional to the product of masses and inversely proportional to the square of distance between them.
Gravitational force depends on mass. The bigger the mass, the more the magnitude of the gravitational force. Since plane is assume to have the highest mass in the options, we can therefore conclude that plane will experience the highest gravitational force.
Answer:
The magnitude of electron acceleration is

Explanation:
Given:
Distance from the wire to the field point
m
Speed of electron 
Current
A
For finding the acceleration,
First find the magnetic field due to wire,

Where 

T
The magnetic force exerted on the electron passing through straight wire,

N
From the newton's second law

Where
mass of electron
kg
So acceleration is given by,



Therefore, the magnitude of electron acceleration is
